Science and Materials in Nature

Hello learner, welcome to an exciting adventure into the heart of science!

In this section, we will uncover the secrets of nature by exploring its defining characteristics. Get ready to dive deep into the wonders of empirical evidence, consistency, objectivity, systematic, creativity, and community that shape the essence of scientific inquiry. This will enhance your critical thinking skills, encourage curiosity, promote healthy scepticism and foster lifelong appreciation for science and its role in society. We will further explore the exciting world where science and design intersect. We will discuss how scientific principles can enhance the quality and credibility of design projects and identify the characteristics of science, describe and provide examples of how these characteristics are applied in scientific inquiry. We will also apply scientific principles to a design project and formulate hypotheses related to their design project and design experiments or investigations to gather relevant data. Again, we will evaluate the impact of scientific design project for future design work and consider how scientific thinking can enhance the credibility and validity of design outcomes. Lastly, you will effectively communicate your project findings using scientific principles to explain your design process and outcomes. In this section we will identify and describe how characteristics of science are applied in both our everyday life and activities as well as other areas in health, agriculture, industry and among others. Let’s embark on a journey of discovery unlike any other as we unlock the mysteries of science.

At the end of this section, you should be able to:

i. Explain the Characteristics of Science in Nature

ii. Design Project Using the Characteristics of Science.

iii. Apply the Characteristics of Science Where Appropriate Learners at the end of this section will be able to:

• Explain the term science

• Identify at least three important aspects of science

• Explain the characteristics of science

• Identify the characteristics of science

• Apply scientific principles to a design project

• Evaluate the impact of scientific design on the design project

• Communicate the findings of the design project using scientific principles

• Identify areas where characteristics of science can be applied

• Describe with specific examples and illustrations how characteristics of science is applied in the home, school, health, education, industry, agriculture among others

• Evaluate how the characteristics of science are applied in the areas mentioned above.

Key Ideas

• Science is a body of knowledge and series processes that help us to understand the natural world and solve problems.

• Science is empirical (based on or derived from observations and data gathered through experimentation or observation of the natural world.).

• Scientific knowledge is replicable (the results of one study can be consistently reproduced by another study using the same methods and tools).

• Science is systematic (the scientific process follows a consistent approach, with clear steps for hypothesis testing, data collection, analysis, and interpretation.)

• Science is consistent (the ability of scientific findings to be reliable and repeatable over time).

• Science is tentative (scientific knowledge and understanding are not fixed or absolute but are subject to change and revision as new evidence, data, and insights emerge).

• Science is predictable: ability of scientific investigations to make accurate and reliable forecasts about future events or phenomena based on established scientific principles.

• Science is valid refers to how scientific observations, data, and measurements accurately reflect the phenomenon under study.

• Science is precise refers to the degree of accuracy, consistency, and reproducibility of scientific knowledge and ideas.

• Science is accurate refers to the correctness or truthfulness of scientific information or measurements.

• Design is the process of creating a plan or specification for the construction, production, or arrangement of an object, system, or structure.

• Scientific design refers to the application of scientific principles and methodologies in the process of designing experiments, studies, or research projects.

• A project is an endeavour undertaken to create a unique product, service, or result. It is a planned and organized effort with defined objectives, specific tasks, and a predetermined time frame.

• Application refers to how knowledge in the characteristics of science is used to produce ideas and/or manufacture products.

• Falsifiability is the capacity of a hypothesis or theory to be proven false if it is indeed incorrect.

Figure 1.1: Learners testing the magnitude of load their paper tower could carry using sachets of water.

Now, learner, look at figure 1.1 carefully and discuss what you see with your neighbours.

Activity 1

In pairs, use the activity in the picture to explain what science is. Note:

suggested answers or conclusions for activities can be found in Annex 1.

Let us explore further with the following activity:

Activity 2

Home-made distilled water Scenario: You are at a camp, and you need water to wash. The only water available is sea/salty water. As a scientist, how do you get the sea/salty water desalinated (water without salt) for washing?

What you need: A deep pot with a lid that is concave if turned upside side (i.e. it is domed if placed on the pot properly), Ice cubes, a bowl to collect your distillate, source of heat, heat towel or napkin, sea water or salty water, liquid soap (to test for the softness of water) What to do:

You can perform this activity alone or in mixed group of not more than five (5) learners:

1. Watch this one-minute video to give you an idea click here

2. Design and conduct your own experiment by selecting your choice of materials from the list given.

3. Write a few sentences which summarise the experiment you conducted today. Remember to include:

• A labelled diagram of your set up.

• A numbered list of instructions (so it could be reliably repeated by another student)

• A discussion of your results, and how these link (or do not link to the expected observations)

Figure 1.2: Simple distillation technique Testing for softness and hardness of the distillate

1. Take equal amounts (about 100ml) of a sample of your distillate and sea/ salty water in separate plastic water bottles of same size and volume.

2. Add a teaspoon full of liquid soap to each sample.

3. Shake the bottles with their contents and compare their reactions in them.

4. Record and discuss your observations.

Safety:

• Make sure that bowls for heating can withstand boiling water.

• The collected distillate should not be consumed, eating, or drinking in a laboratory is against lab safety rules.

• Use heat towel/napkin to prevent burns on the fingers.

• Only the water in the collecting bowl will have distilled water. The remaining water will contain all the impurities you removed from the distilled water.

• Always secure bottle caps tightly before shaking to avoid spillage.”

• Clean up any spills immediately while following proper disposal guidelines for the materials used.

Conclusion: Only the water in the collecting bowl will have distilled water.

The remaining water will contain all the impurities you removed from the distilled water.

Hello learners, I am sure you had an exciting time with activity 2. The knowledge from this activity can be used to explain the water cycle where evaporation (boiling of water) separates water from contaminants/impurities (salt and others in water) and condensation (on the lid) returns it to a liquid state, free from minerals and contaminants.

Interesting, isn’t it? Great.

Let us explore the importance of science with the next activity.

Activity 3

The Egg Drop Challenge

Scenario: There is egg crisis in senior high schools in Ghana! The Ghana Education Service is organising a famous Egg Festival for senior high schools, which is just around the corner, and the Director General has ordered rare, delicate eggs from poultry farmers around the country for the festival’s grand egg painting competition. However, during transportation, the delivery truck accidentally drove over a pothole, causing the eggs to be pushed and shaken.

As a result, many of the eggs were cracked, leaving the students in a state of anxiety. The Director General has called upon the SHS 1 science classes to use their knowledge of science to salvage the situation. You are tasked to design and build a gadget to protect the remaining eggs from breaking when dropped from a height of 2.0m.

What you need: Raw eggs (enough for each group to have one), marker, various materials (e.g., straws, cotton balls, tape, popsicle sticks, rubber bands, balloons, paper cups, cardboard, bubble wrap, etc.) for building an egg protective structure, scissors, a designated dropping area (like a balcony, staircase, or simply a maximum height of 2.0m from which the eggs can be dropped).

Figure 1.3: Homemade materials for egg drop challenge What to do:

Pair with a friend or form a mixed group of not more than 5 learners.

1. Generate ideas and agree on a design, select appropriate materials and build your egg protective structure.

2. Present your design to the class, explaining the scientific principles behind your choices of materials and construction.

3. Conduct the egg drop test: Each group takes turns to use their structure to drop an egg from a designated height (2.0m). If the egg breaks, the group is out of the challenge.

4. Discuss the results as a class, focusing on what worked well and what could be improved.

5. Analyse the scientific concepts involved, e.g. forces acting, etc.

6. Share your experience of the importance of science.

Through the Egg Drop Challenge, you have not only learned about scientific principles but also gained practical experience in applying those principles to solve real-world problems. You have also learned the importance of collaboration (teamwork) and repetition in the scientific process.

Thus learners, What is the importance of science?

Take a moment here to reflect on how science has improved your daily life. Think about the experimentation that will have gone into all the aspects of your life touched by science.

Conclusion: Record here your thoughts of what the biggest achievements of science have been, and what you think they could be in the future. After produc- ing your own share these with your neighbour and discuss what they have pro- duced.

Science has a special role, as well as a variety of functions for the benefit of our society:creating new knowledge, improving education, and increasing the quality of our lives.

Good job learners, let us continue our exciting journey with a look at the characteristics of science.

The Characteristics of Science

Key Question

Why is it essential for scientists to base their conclusions on evidence?

Record your thoughts or those of the class here:

Let us look at the key characteristics of science, such as being empirical, reproducible, systematic, consistent, tentative, predictable, valid, precise and accurate. Let us discuss each of the characteristics and their application.

Are you ready?

Good!

Picture the first characteristic: ‘Empirical’.

What does it mean then to say science is empirical?

Record the thoughts of the class here:

Empirical: This means it relies on systematic observations and data gathered through experimentation or observation of the natural world. These observations are used to formulate hypotheses and theories.

In science, we do not rely solely on speculation or hearsay. Instead, we embrace empirical evidence. It is like detectives gathering clues to unravel a mystery, except our mystery is the natural world itself.

I am sure you are eager to explore more.

Let us do an activity!

Activity 4

Experiment to show that science is empirical Title: Determining the Boiling Point of Pure Water at Sea Level Key Questions:

a. What is the boiling point of water?

b. How does altitude affect the boiling point of water?

c. Why is it important to know the boiling point of water?

d. How can you measure the boiling point accurately and reliably?

Aim: To verify that the boiling point of pure water remains constant at sea level.

Hypothesis: The boiling point of pure water at sea level is 100 degrees Celsius (212 degrees Fahrenheit).

Key Questions (record your thoughts alongside each question):

a. What materials do you need for this experiment?

b. How should you set up the apparatus to ensure accurate results?

c. Why is it important to use distilled water in the experiment?

d. What safety precautions should you take when conducting the experiment?

What you need Heat source (e.g., Bunsen burner/electric stove/coal pot), a beaker or any suitable heat-resistant container, thermometer (that will measure up to 100 degrees Celsius), water (free from impurities), stopwatch or timer.

NB: rainwater should be collected from a height above the ground to prevent being contaminated by impurities.

Data Collection and Observation

Key Questions (In your view, suggest answers to these questions):

a. What are the signs that water is boiling?

b. How can you ensure that you accurately record the boiling point?

c. What factors might affect the accuracy of your measurements?

d. How can you maintain consistency in your observations?

Procedure:

1. Fill the beaker or container with a fixed volume of water (e.g., 100 ml).

2. Insert the thermometer into the water without touching the bottom of the receptacle.

3. Place the beaker or container on the heat source.

4. Gradually increase the heat and monitor the temperature using the thermometer.

5. As the water temperature rises, observe and record the changes in temperature.

6. When the water boils, note the temperature and start the timer.

7. Continue boiling the water and monitor the temperature every 30 seconds for a few minutes.

NB: Repeat the experiment using water from at least three different sources.

Figure 1.4: set-up to determine the boiling point of water.

Analysis and Conclusion

Key Questions (In your view, suggest answers to these questions):

a. What was the observed boiling point of water at sea level?

b. How does your experimental result compare to the standard boiling point of water (100°C or 212°F)?

c. What factors might have influenced any discrepancies in your results?

d. How can you improve the accuracy of your experiment in future trials?

Next is ‘Consistency’. Nature is believed to operate according to consistent patterns and laws. Through scientific investigation, we strive to uncover these underlying principles, from the elegant laws of motion to the intricate principles governing genetics. This consistency allows you to make predictions and understand the Universe’s inner workings.

Consistency, therefore, refers to the ability of scientific findings to be reliable and repeatable over time. It also means that other scientists can replicate experimental results using the same methods and procedures and that the findings are consistent with what is already known about the phenomenon being studied.

Why do you think that consistency is an important principle of Science? Imagine what science would be like without it. Record your thoughts and those of the class here:

Let us look at reproducibility as the next characteristics.

Reproducibility- Scientific research must produce results that others can repeat using the same methods and conditions.

Let us do an activity!

Activity 5

Experiment to show that science is consistent and replicable (reproducible) Title: The Simple pendulum experiment Aim: To conduct a simple experiment involving a pendulum to demonstrate that scientific results should be consistent and reproducible if the same methods are used, and factors are kept uniform.

Key Questions (Put your ideas on paper as you read each question)

i. What is the purpose of your experiment with the pendulum?

ii. How will you ensure that your experiment is reproducible by others?

iii. What factors do you need to consider and keep uniform throughout your experiment?

iv. How will you measure and record the variables involved in the pendulum experiment?

v. Why is it important to repeat the experiment multiple times with the same methods and conditions?

vi. What conclusions can you draw from replicating the experiment with the same methods and variables?

What you need A sturdy string or thread, a small weight (e.g., a metal ball or a stone), a ruler or measuring tape, a stopwatch or timer, a stable point to hang the pendulum (e.g., a hook or a sturdy table edge or retort stand) What to do

1. Attach the weight to one end of the string/thread securely.

2. Hang the other end of the string/thread from a stable point.

3. Measure and record the pendulum’s initial length: Use the ruler or measuring tape to measure the pendulum’s length (from the point of suspension to the centre of the weight). Record this length as “L” (initial length).

4. Hold the pendulum at a measured and fixed distance away from its resting position and release it from the same starting point each time.

5. Time the pendulum swinging to and fro ten times using the stopwatch or timer.

6. Record the time taken for the swings.

7. Repeat the experiment three times and compare the times taken for ten swings.

8. Change the length of the string (by shortening or lengthening it) and repeat the swinging process to and fro ten swings and record the time.

Analyse the data:

i. Compare the results for each repeat of the experiment.

ii. How do the results vary among the three repeats of the experiment?

iii. Are the results the same? If not, what reasons could account for the variability?

iv. Does changing the length of the string change the time taken for ten swings to and fro?

v. Compare your results with those of other groups in the class, do your findings agree with theirs?

Figure 1.5: set-up for a simple pendulum experiment Well done learners, let us turn our attention to another characteristic.

vi. What does it mean to say science is systematic in nature? Record your initial thoughts and those of the class here Systematic methodology- This means scientific process follows an organized approach, with clear steps for hypothesis testing, data collection, analysis, and interpretation.

Let us do an activity!

Activity 6

Experiment to show that science is methodical (systematic) Title: Investigating the presence of starch in plants.

Provide possible answers to key questions A, B and C.

Key Question A (record your thoughts alongside these questions):

i. What is starch, and what role does it play in plants?

ii. Why is it important to study the presence of starch in plants?

iii. How can you test for the presence of starch in plant materials?

iv. What are some common sources of starch in the human diet?

Aim: To test the presence of starch in plants.

Key Questions B (record your thoughts alongside these questions):

i. What materials do you need for this experiment?

ii. How should you prepare plant samples for testing?

iii. What reagents or chemicals are required to test for the presence of starch?

iv. How can you ensure that your experimental set-up is consistent and accurate?

What you need: Test tubes, test-tube stand, test-tube holder, heat source (e.g.electric kettle), dropper, filter paper, iodine solution, ethanol (alcohol), distilled water, green leaf.

Key Question C (record your thoughts alongside these questions):

i. What are the steps involved in conducting the starch test(s)?

ii. What are the expected results if starch is present in the plant samples?

What to do:

i. Gather leaves from plants exposed to sunlight for a minimum of 2 hours for testing.

ii. Pour boiling water from the electric kettle into a large beaker.

iii. Using forceps immerse a leaf in the hot water for three minutes.

iv. Remove the leaf from the boiling water with forceps and observe any changes. Record your observation in your science jotter.

v. Transfer the leaf to a labelled boiling test tube pushing it to the bottom with a glass rod.

vi. Fill the boiling test tube halfway with ethanol and place it in a hot water bath at 80 degrees Celsius for three minutes.

vii. Observe as the ethanol boils and record any changes observed.

viii. Remove the leaf from the boiling ethanol using forceps, rinse it under cold water.

ix. Gently place the leaf in a Petri-dish or a white tile and add iodine solution, ensuring complete coverage.

x. Record your observations.

Figure 1.6: Steps for testing starch in green leaf Safety:

• Keep the ethanol away from naked flames.

• Wear eye protection when working with ethanol or iodine solution to prevent chemicals from getting in contact with the eye.

• Take care with hot liquids.

• Be aware that plant sap may irritate the skin.

Observation:

After a few minutes, observe the development of a blue-black colour indicating the presence of starch.

Key Question D (record your thoughts alongside these questions):

i. What were the results of the starch tests for each plant sample?

ii. How do the results compare to your expectations?

iii. What factors might have influenced any differences in the results?

iv. How can you interpret the presence or absence of starch in different plant samples?

Consider now the concept of science being systematic. In the experiment just completed how did we determine beyond doubt that starch is present?

How did we ensure that our process was trustworthy? And that a casual observer would not think we were lying to them?

Well done learners. Let us discuss other characteristics Tentative- This means that scientific knowledge and understanding are not fixed or absolute but are subject to change and revision as new evidence, data, and insights emerge. Can you think of any examples where this has happened? Either in recent memory or throughout history?

Predictability- refers to the ability of scientific investigations to make accurate and reliable predictions about future events or phenomena based on established scientific principles. Think of any unexpected events or findings that led to important changes, either in recent history or in the past?

Validity- refers to how scientific observations, data, and measurements accurately reflect the phenomenon under study. When scientific findings are valid, they are based on sound reasoning, empirical evidence, and rigorous scientific methods, with minimal influences from extraneous factors.

Let us consider two more characteristics, precision and accuracy! Let us read about them.

Precision- refers to scientific measurements’ degree of accuracy, consistency, and reproducibility. Precise scientific measurements consistently produce similar results over multiple trials, with minimal deviation, error, or uncertainty.

Accuracy- refers to the correctness or truthfulness of scientific information or measurements. When scientific findings are accurate, they reflect the true nature of the phenomenon under study, with minimal errors, bias, or distortion.

Great learners, let us do an activity!

Activity 7

Experiment to determine whether given substances are acidic or basic.

What you need: red and blue litmus paper (you can also use red hibiscus petals/sobolo leaves to dye a filter paper, dry it and use as your home made litmus paper), orange juice, wood ash, vinegar, baking soda, unripe lemon, carbonated water, liquid soap, tomato juice, calcium carbonate (you can get it by grinding eggshells into powder), salt Petre. Milk of magnesia, calcium hydroxide powder (carbide waste from welder’s shops can be used).

What to do:

Pair with a friend or in mixed group of not more than 5 learners.

1. Using red and blue litmus papers, test whether the following substances are acids or bases and present your findings in a table as shown below.

Test substances Observation Conclusion Red litmus Blue litmus Orange juice Wood ash solution Vinegar Unripe lemon juice Carbonated water Bicarbonate of soda

solution

Liquid soap Tomato juice Calcium carbonate

solution

Salt Petre solution Milk of magnesia Carbide waste solution

2. Identify the characteristics of science involved in this experiment and explain your answers.

Hello, learners. I hope you enjoyed the activity and can confidently explain the characteristics of science.

Activity 8: Creating a poster showing the key characteristics of science.

What have you learned in this session? Create a poster showing the key characteristics of science, explaining the significance of science and defining any terms used. Prepare your presentation for a whole-class gallery walk.

(Note: see Annex 1 for some hints).

Activity 1

Science is not merely a subject to study or a collection of facts to remember;

it is an exciting process. It is a way of thinking that encourages curiosity, questioning, and a deeper understanding of the world around us. All through your years at the basic level, you learnt about science by performing a number of experiments, recorded data and made inferences about natural phenomena.

You will have gained deeper knowledge about the natural world and as a result can solve problems. Science is driven by curiosity, the insatiable desire to know and understand the natural world.

Thus, Science is the observation, identification, description, experimental investigation, and theoretical explanation of natural phenomena to widen people’s understanding of nature and solve problems.

Activity 2

Expected Observations: The distillate is colourless, odourless and tasteless and easily forms lather with soap. Unlike the sea/salty water which does not easily lather with soap.

Activity 3

You will agree that from activity 3, you used your scientific knowledge to solve the problem in the real world. Your solution was made possible through creativity and innovation. Science is therefore an important channel of knowledge necessary for creation.

a. Similar to the above, scientific knowledge has brought some innovations like the creation of computers, satellites, x-rays, and cell phones which has proven invaluable. Other importance include:

b. Science enhances global understanding - being able to accurately predict the weather has enabled agriculture to flourish worldwide.

c. Scientific Research boosts health (yielding medications, vaccinations, and therapies) - extending lifespans and improving the quality of lives.

d. Science has improved diverse transportation modes in automobiles, aircraft, ships, and space exploration among others.

Activity 4

Expected Results:

According to the hypothesis, the boiling point of water at sea level is expected to be 100 degrees Celsius (212 degrees Fahrenheit). Therefore, during the experiment, you will observe that the water boils at this temperature and remains constant as long as it continues to boil.

Conclusion:

It can be identified that the boiling point of water without impurities at sea level remains constant at 100°C or 212°F. This allows you to accept your hypothesis. As the results are collected scientifically and agree with your hypothesis, you have demonstrated the use of empirical measurement in the testing and confirmation of the scientific hypothesis as a fact.

NB: Sea level refers to the level of sea at normal atmospheric temperature and pressure. These may differ from the conditions in our laboratory.

Activity 5

Conclusion:

The time taken for ten swings to and fro should be very similar for the three repeats of the experiments as long as the length of the string and the point of release are kept uniform. Thus, properly designed and executed experiments are consistent and replicable.

Any small variability in the results will be down to errors of timing or small inconsistencies in the height of release of the experiment. Increasing the length of the pendulum string should increase the time taken for ten swings.

Activity 6

Conclusion The leaf turning blue-black is an indication that photosynthesis has taken place and starch has been prepared as a result.

Activity 7

1. Systematic, observation, empirical, verifiable, etc.

Activity 8

You have learned that:

1. Science is the observation, identification, description, experimental investigation, and theoretical explanation of natural phenomena to widen people’s understanding of nature and solve problems.

2. The importance of science is that it helps us to understand the world better, improves our standard of living, and makes life easier and more comfortable.

The key characteristics of science include empirical, reproducible, systematic, consistent, tentative, predictable, valid, precise and accurate.

A scientific project design is a systematic plan for conducting scientific research or investigation. It outlines a particular scientific study or experiment’s objectives, methods, procedures, and expected outcomes.

Activity 9: Discussing characteristics of science in the design of scientific projects Key Questions (Note: solutions can be found in Annex 2)

1. Let’s start by understanding what makes science unique. From the previous session, you discussed the characteristics of science that guided inquiry and helped generate reliable knowledge. List some of these characteristics.

2. What are some of the ways you can incorporate scientific principles into the design of a project?

Now, let us discuss the impact of scientific design on your project. When you incorporate scientific characteristics, such as empirical methods and falsifiability, you can make your project outcomes more reliable and credible.

3. How do you think scientific design can influence the quality of your project?

Lastly, you can effectively communicate your design project findings using scientific principles. It’s important to present your work in a clear and structured manner, following scientific communication standards.

4. What other ways can you effectively communicate your design findings using scientific principles?

Examples of projects that require scientific designs are investigating the effects of different fertilizers on plant growth, relationship between the period of a pendulum and its length, investigating acid-base properties using hibiscus flower juice indicator, construction of solar oven for cooking and many more.

In the section, you performed various experiments to verify each of the scientific characteristics. In this section, you are using these characteristics to design scientific projects.

Project Design Activities

In this section, you will do activities to explore various designs that focus on specific characteristics. You will be engaged and have the chance to interact with them first-hand.

Now, in groups of six you are to design the following real-world projects and identify which of the characteristics relates to that project. You will find suggested answers in Annex 1.

NB: (The above instruction applies to all the activities in this section)

Activity 10: Investigating the effects of different fertilisers on plants growth Title: A design for investigating the effects of different fertilizers on plant growth Aim: To come out with a design to be used to apply the characteristics of science to investigate the effects of different fertilizers on the growth of plants.

The Design

1. Select sixty identical seedlings of the same plant species (e.g., tomato plants). All the seedlings must be of the same age.

2. Divide them into three equal groups.

3. Plant seedlings into soil.

4. Assign each group a different fertilizer treatment. For example, Group 1 could receive a commercial chemical fertilizer (NPK) of 20cm³, Group 2, an organic fertilizer of about 1kg (equivalent to 20cm³of chemical fertilizer, and Group 3, a control group with no fertilizer.

Fig 1.7: Learners applying fertilizer on plants NB: Ensure all groups receive the same environmental conditions (e.g., light, temperature, water).

Observation: Observe, measure and record the plants’ height and number of leaves at regular intervals of three days over a set period (e.g., six weeks)

Table 10: Sample table Day Group 1 Group 2 Group 3 Mean Height Mean Number of Leaves Mean Height Mean Number of Leaves Mean Height Mean Number of Leaves 0 3 6 9 12 15 Analysis and discussion Analyse the collected data using statistical methods (for example, plot average values against time on the graph with a different line for each treatment) to compare plants growth patterns across different fertilizer treatments.

Discuss the implications of the findings, including potential applications in agriculture and areas for further research.

Conclusion Draw conclusions based on the results obtained, considering the effects of different fertilizers on plant growth and any significant differences observed.

Activity 11: A project on a solar oven Title: Produce a solar oven Aim: Produce a solar oven to be used for cooking at home.

Material: cardboard box, Box knife or scissors, Aluminium foil, Clear tape, Plastic wrap, Black construction paper, Newspapers, Ruler or wooden spoon, Thermometer, chocolate, marshmallows, graham cracker Fig 1.8 : Learners constructing solar oven Methods:

i. Using a pizza box and knife cut a flap in the lid, leaving one inch between the edge of the box and where you cut. This is shown in Fig.1.9: stage 1

ii. Fold the flap out to stand up when the box lid is closed.

Fig 1.9 : Stage 1

iii. Cover the inner side of the flap with aluminium foil folding the edges of the foil over the flap to keep it in place. Tape down the foil and try to keep it as smooth as possible.

Fig 1.10 : Stage 2

iv. Lift the lid and line the inside of the box with aluminium foil – shiny side out.

v. Cover the opening made in the box lid by the flap with plastic wrap. The wrap should be as airtight as possible. Tape the plastic wrap in place.

Fig 1.11 : Stage 3

vi. Cut a piece of black construction paper so that it’s 2 inches smaller along each edge than the bottom of the box. If you have a large box, you might need more than one piece of paper.

vii. Centre the construction paper in the centre of the bottom of the box, on top of the foil. Tape in place. This is shown in Fig.1.12; stage 4.

Fig 1.12 : Stage 4

viii. Take newspapers and make four rolled tubes of newspaper out of multiple sheets of paper. Each of these rolls will go along the edges on the inside of the box, creating a border. Tape the rolls in place. Be sure the rolls do not stop the lid from closing. This is shown is Fig.1.13: stage 5.

Fig 1.13 : Stage 5

ix. Using a pencil, create a “dent” in the box, where you can insert the pencil and use it as a “kickstand” for the lid to remain upright for cooking Fig 1.14 : Stage 6

x. The solar oven is ready to be set outside on a sunny day while the sun is high overhead, between 11 AM and 2 PM when the sun’s rays are the strongest. Put the graham cracker, topped with a piece of chocolate, and a marshmallow in the oven.

Fig 1.15 : Complete Solar Oven

xi. Close the lid. Prop up the flap you cut and lined with aluminium foil using the pencil.

xii. Let the sun do its work! It will take some time.

Discussion: With a peer or group of peers, discuss the design of the oven and consider improvements that could be made to make it more efficient.

Consider how the efficiency of different solar ovens could be measured; write a brief method for your suggested investigation.

Activity 12: Building a balloon-powered car Title: Balloon-powered cars Aim: Design and build your own balloon-powered car Suggested materials: Plastic bottle (empty and clean), Straws (plastic or paper), Balloon, Bottle cap, Rubber bands, Four bottle caps (for wheels), Tape (duct tape or masking tape), Scissors, Cardboard or foam board (for making the car body), Pen or marker.

See the picture below for an example of how your balloon-powered car may look, although you may choose a different design!

Hint:

Do some background research on balloon-powered cars. Do an internet image or video search for “balloon powered car” and you will see many different designs, made from different materials. This can inspire your design.

Think about what materials you want to use for your car, and how you will connect the different pieces together. For example, what do you want to use for wheels?

Make a sketch of your design on paper before you start building.

Observation:

It will be observed that the air escaping from the balloon will propel the car forward.

Suggest an alternative way to improve the performance of your car if it doesn’t move as expected.

Activity 13: Tentative nature of science Title: The Pendulum Experiment - Demonstrating the Tentativeness of Science Aim: To conduct a simple experiment involving a pendulum to demonstrate the tentative nature of science by observing how different factors can influence the pendulum’s behaviour and how scientific conclusions may evolve based on additional data and analysis.

Materials: A sturdy string or thread, a small weight (e.g., a metal ball or a stone), a ruler or measuring tape, a stopwatch or timer, a stable point to hang the pendulum (e.g., a hook or a sturdy table edge) Procedure:

1. Set up the pendulum:

• Attach the weight to one end of the string/thread securely.

• Hang the other end of the string/thread from the stable point.

2. Use the ruler or measuring tape to measure the pendulum’s length (from the point of suspension to the centre of the weight). Record this length as “L” (initial length).

3. Conduct the pendulum swing experiment:

• Hold the pendulum away from its resting position and release it from the same starting point each time.

• Time the pendulum for a fixed number of swings (e.g., 10) using the stopwatch or timer.

• Record the time taken for the swings.

4. Change variables:

• Experiment multiple times while changing one variable at a time.

For example, you can alter the pendulum’s length (by shortening or lengthening it) or change the amplitude (the angle at which you release the pendulum).

• Record the results for each variation, including the new length of the pendulum or amplitude and the corresponding swing time.

5. Analyse the data:

• Compare the results for each variation of the experiment.

• Look for patterns and relationships between the length/amplitude and the swing time.

Discuss how changing different variables affects the pendulum’s behaviour and consider why scientists often revise their models as new investigations are carried out.

Activity 14: Experiment to demonstrate various characteristics of science Choose one of the experiments that you carried out during week 2 and present your findings from the experiment to the class, including an analysis of how the experiment demonstrates various scientific principles and how the method could be adjusted in order to produce more reliable results.

Extended Reading

Access and use the following sources and resources to find out about designing scientific project and show which of the characteristics of science that have been involved.

1. Internet resources such as Massive Open Online Courses (MOOCs)

2. https://evolution.berkeley.edu/nature-of-science/characteristics-of-science/and

3. https://www.sciencebuddies.org/science-fair-projects/project-ideas/list)

4. https://evolution.berkeley.edu/nature-of-science/characteristics-of-science/and

5. https://www.sciencebuddies.org/science-fair-projects/project-ideas/list

6. https://evolution.berkeley.edu/nature-of-science/characteristics-of-science/and

7. https://www.sciencebuddies.org/science-fair-projects/project-ideas/list)

8. https://evolution.berkeley.edu/nature-of-science/characteristics-of-science/and

9. https://www.sciencebuddies.org/science-fair-projects/project-ideas/list)

Activity 9

1. Some of the key characteristics of science include empiricism, and replicability. These characteristics play crucial roles in ensuring the reliability and validity of scientific knowledge.

2. You can apply scientific principles by using empirical methods, such as collecting and analysing data, to inform your design decisions. You can also formulate hypotheses related to your design goals and create experiments or investigations to gather data that supports or challenges those hypotheses. By using scientific principles, you can make your design process more systematic, and evidence based.

3. It must be noted that scientific design helps you to gather accurate data, make informed decisions, and ensure that your design outcomes are based on evidence rather than assumptions. It also allows you to critically evaluate your design choices and make improvements based on the findings of your experiments or investigations. By applying scientific principles, you can create more effective and successful design solutions.

4. When communicating your design findings, you should use scientific terminology and concepts to explain your design process and outcomes.

You should present your data, analysis, and conclusions in a way that others can understand and evaluate. By using scientific principles in your communication, you can ensure that your findings are transparent, credible, and accessible to others.

Activity 10

Examples of Characteristics of Science Applied in the above project Empirical: The project will involve conducting experiments and collecting empirical data by observing and measuring the growth of plants.

Objective: The project will follow standardized methods of experimentation to minimize bias and subjectivity. Care will be taken to ensure accurate and unbiased measurements and observations.

Verifiable: The project will formulate testable hypotheses regarding the effects of different fertilizers on plant growth. The results obtained will help determine if the hypotheses are supported or contradicted.

Replicable: The experimental set-up and procedures will be documented to enable other researchers to replicate the study and verify the findings. The project will provide detailed instructions and guidelines for replicating the experiment.

Cumulative: The project will contribute to the cumulative body of scientific knowledge by adding new data and insights to the current understanding of the effects of fertilizers on plant growth.

Tentative: The project recognizes that scientific knowledge is tentative and subject to revision. The findings will be interpreted within the context of current understanding and may lead to modifying or refining existing theories or practices.

Predictive: The project will analyse the data collected to predict the effects of different fertilizers on plant growth. These predictions can serve as a basis for further experimentation or practical applications in agriculture.

Activity 11

Examples of Characteristics of Science Applied in the above project Empirical: Through experiments and observations, students can gather empirical evidence to support the effectiveness of their solar oven design.

Systematic: The design and construction of a solar oven follows a systematic approach. Students need to develop a clear plan, consider different variables, and organize their experiment in a logical manner. They will systematically test and modify their design to optimize its performance.

Testable and Falsifiable: The experiment to construct a solar oven involves formulating hypotheses about how different design elements will affect its cooking efficiency. These hypotheses are testable by conducting experiments and measuring the oven’s performance. If the results do not align with the predictions, the hypotheses can be revised or rejected.

Replicable: The experiment should be replicable, meaning that other individuals should be able to follow the same instructions and construct a similar solar oven. Replicability allows for the validation of results and the verification of the oven’s cooking capabilities.

Tentative: The knowledge gained from the experiment is tentative in nature.

Students may discover new insights, encounter unexpected challenges, and make adjustments to improve their solar oven design. The experiment’s outcomes can lead to further revisions and refinements in the understanding and construction of solar ovens.

Cumulative: The experiment contributes to the cumulative knowledge in the field of solar energy and cooking. The findings from the experiment can be shared with others, building upon existing knowledge and inspiring further research and innovation in solar oven design and applications.

Activity 12

Examples of Characteristics of Science Applied in the above project Empirical: Constructing a balloon-powered car involves empirical observation and experimentation. Students test different designs, materials, and configurations to determine how they affect the car’s performance. They gather empirical evidence through observations and measurements to support their conclusions.

Systematic: The experiment follows a systematic approach. Students develop a plan, identify variables, and design controlled experiments to test specific hypotheses. They systematically vary factors such as balloon size, car weight, or wheel material to understand their impact on the car’s speed and distance travelled.

Testable and Falsifiable: Hypotheses can be formulated and tested in balloon- powered car experiments. For example, a hypothesis might be that increasing the size of the balloon will result in greater propulsion and increased speed.

The hypothesis can be tested by constructing cars with different balloon sizes and measuring their performance.

Replicable: The experiment should be replicable by others. Detailed instructions and specifications should be provided so that other students or researchers can construct similar balloon-powered cars and reproduce the results. Replicability allows for validation and verification of the experiment’s findings.

Tentative: Knowledge gained from the experiment is tentative and subject to revision. Students may discover unexpected results or encounter challenges that require them to revise their initial hypotheses or redesign their cars. The experiment promotes a willingness to revise and refine understanding based on new evidence.

Cumulative: The experiment contributes to the cumulative knowledge in the field of balloon-powered vehicles. Students’ findings can be shared with others, building upon existing knowledge and inspiring further experimentation and innovation in the design and performance of balloon-powered cars.

Activity 13

By conducting the pendulum experiment and analysing the data, participants will realize that scientific conclusions are tentative and subject to change based on various factors and evidence. They will understand the importance of considering different variables and the limitations of a specific experiment in drawing scientific conclusions. This experiment is a tangible example of how science is an ongoing process of learning and refinement.

Examples of Characteristics of Science Applied in the above Project Empirical Evidence: The experiment relies on direct observation and measurement of the relationship between pendulum length and period.

Systematic Observation: The experiment follows a systematic procedure, changing one variable (length) while keeping others constant to observe its effect.

Predictive Power: By analysing the relationship, you can predict how changing the length of the pendulum will affect its period.

Objectivity: By ensuring the mass of the weight used is constant, the type and length of string is kept constant and there is an agreed protocol for measuring the length o the pendulum, bias is removed, and the experiment can be considered objective.

Testability: The hypothesis that the length of a pendulum depends on its length is testable through experiment. By conducting this experiment and analysing its results, you can gain a deeper understanding of the characteristics of science within the realm of physics.

We engage in various activities in our everyday life. Sometimes you argue with friends, bring out ideas or options for how to solve a problem and then finally agree on the option you believe will work. With your knowledge on characteristics of science from your previous discussions, we will discuss how they are applied in areas like the home, school or education, health, agriculture and industry. In your small groups, you can list other areas of your community you think these scientific characteristics are applied.

Application of Characteristics of Science in Health

and Medicine

Activity 14: Discussing characteristics of science in medicine Discuss with your friends how the characteristic of science were applied in medicine, for example in discovering vaccines for COVID-19 during the pandemic. You can use your search engine to surf the internet to help you with the facts.

Fig. 1.16: Scientists discovering vaccines in the laboratory Application of Characteristics of Science in the Home We apply characteristics of science in our everyday life including the home. Let us go through the following activity and point out which of these characteristics are applied.

Activity 15: Application of characteristics of science in cooking In your small group

i. Use Fig. 1.17 to help you Identify a meal of your choice.

ii. Discuss where and how you will get the ingredients to prepare the meal.

iii. Describe among yourselves the steps involved in cooking that meal.

iv. Analyse the scientific characteristics were applied in the process of your discussions (Note: suggested answers are in Annex 1).

v. Present your findings to the class.

Fig. 1.17: A woman cooking Application of Characteristics of Science in School or Education Formal education like learning General Science occurs in the school.

Activity 16: Application of characteristics of science in school Describe what you see in Fig. 1.18, and consider which of the scientific characteristics are involved in school.

Fig. 1.18: Learners performing experiment in the science laboratory.

Application of Characteristics of Science in

Agriculture Having gone through application of the characteristics of science in the home, let us discuss how it applies in agriculture.

Fig. 1.19: Agriculture research

Activity 17: Discovering characteristics of science in agriculture Observe the image in fig.1.19

i. describe what you see with your friends

ii. which crops do you think go through a similar process in the image?

iii. explain among yourselves the types of characteristics of science that is applied in the process above.

Application of Characteristics of Science in

Industry

Activity 18: Explanation of characteristics of science.

Explain the types of characteristics of science that are applied in industry.

Extended Reading

Poster pictures showing scenarios in which the characteristics of science are displayed.

https://evolution.berkeley.edu/nature-of-science/characteristics-of-science/ https://www.sciencebuddies.org/science-fair-projects/project-ideas/list

Review Question 1

Exercise 1 Crossword Puzzle

Use the clues to fill in the words below.

• Words can go across or down.

• Letters are shared when the words intersect.

Across

3. means that scientific knowledge and understanding are not fixed or absolute but are subject to change.

6. refers to the ability of scientific investigations to make accurate and reliable predictions about future events or phenomena based on established scientific principles.

9. refers to the scientific process that follows an organized approach, with clear steps for hypothesis testing, data collection, analysis, and interpretation.

10. relies on observations and data gathered through experimentation or observation.

Down

1. refers to the ability of scientific findings to be reliable and repeatable over time.

2. refers to how scientific observations, data, and measurements accurately reflect the phenomenon under study.

4. means scientific research must produce results that others can repeat using the same methods and conditions.

5. means seeing and accepting facts as they are, not as one might wish them to be.

7. refers to scientific measurements’ degree of accuracy, consistency, and reproducibility.

8. refers to the correctness or truthfulness of scientific information or measurements.

1 2 3 4 5 6 7 8 9 10 Exercise 2 Answer the following questions

1. How would you explain six characteristics of science to your younger student?

2. How would you explain six characteristics of science to your younger student?

3. Ali looks on as his parents make tea using teabags every morning before they go to work. This is to enable him to prepare tea in the future as he grows. As a learner of science identify and discuss the characteristics of science involved in this daily process.

4. An SHS 1 learner is required to use 150cm³of water in an experiment.

As a learner of science show how to measure 150cm³of water using a measuring cylinder and identify any characteristics of science applied.

Research Work

Use the internet and other resources to search for more information about one of the characteristics of science. Think about a historical or current experiment or practice where this characteristic is key. Explain how the experiment or practice you have chosen exemplifies the characteristic and it’s role in Science. Present your report which should include posters, diagrams and charts about your findings to the class.

Review Question 2

1. Name two ways of applying characteristics of science in

i. education

ii. health and

iii. agriculture.

2. People living in a town realised that most the children and some adults were frequently getting ill. The medical reports of those who visited the clinic pointed to malaria infection. As a student of science, how will you apply the characteristics of science to identify the causes?

Imagine a world without solids, no clothing to wear, no smart phones to text your friends, no strong desks to sit on in class, and no bicycles and cars to ride through the park. Sounds awful, right? Well, thankfully, we live in a world filled with an incredible variety of solids, each with its own unique properties and uses. You are about to embark on a journey where you will classify and discover the hidden treasures within different types of solids. Now, think about this: What makes gold so precious, steel so strong, and crystals so fascinating? The answer lies in their composition and properties. In this section, you are not just going to admire these solids from afar. You are going to dive deep into the fascinating world of solids and explore how we can classify them based on their characteristics and discover the amazing ways they shape our lives.

At the end of this section, you should be able to:

• Classify different solids and their uses

• Apply the properties of solids to everyday use.

• Discuss the relationship between binary compounds, the composition of binary compounds and the names of compounds.

Learners at the end of this section will be able to:

• Identify the first 20 elements on the periodic table.

• Identify and classify solids into Metals, Semi-metals, and Non-metals.

• Describe the Properties of Metals, Semi-metals, and Non-metals.

• Outline and explain the Uses of Metals, Semi-metals, and Non-metals

• Identify and describe the properties of solids

• Classify solids based on their uses/properties

• Analyse and describe how the properties of these solids are applied to their everyday use

• Explain binary compounds and identify their general characteristics

• Determine the composition of binary compounds, distinguishing between ionic and covalent binary compounds

• Categorise given compounds as either binary ionic or binary covalent based on their composition

• Predict the properties of binary compounds based on their composition

• Learn how to find the chemical formula of binary compounds.

• Learn how to name a binary compound.

Key Ideas:

• Materials are broadly categorised into metals, non-metals and semi- metals. Each having distinct compositions and characteristics such as conductivity, lustre, and hardness.

• An element is the smallest particle of a pure substance that cannot be broken down into any simpler substance by chemical reactions and is made up of one or more atoms of the same kind.

• The periodic table of chemical elements organizes all discovered chemical elements in rows (called periods) and columns (called groups) according to increasing atomic number.

• An element can be a solid, liquid or gas. A solid is a state of matter which has a definite shape and volume.

• Elements are broadly categorized based on their physical and chemical properties into metals, non-metals, and semi-metals.

• Reactivity: The tendency of a metal to undergo chemical reactions, such as oxidation or displacement reactions.

• Corrosion: The deterioration of metals due to chemical reactions with substances in their environment, such as oxygen or moisture or acid.

• Solids have wide applications and uses in everyday life such as metals for construction, ceramics for electronics, and plastics for packaging.

• Solid materials – refer to substances or objects with a definite/fixed shape and volume.

• Properties of materials:

o Conductivity o Magnetism o Lustre o Melting point o Boiling point o Density

• Binary compounds are chemical compounds composed of exactly two different elements.

• Binary compounds are grouped into two categories: Binary ionic compounds and binary covalent compounds.

• Binary ionic compounds are composed of a metal and a non-metal (e.g., NaCl, MgO, CaCl2).

• Binary covalent compounds are composed of two non-metals (e.g., CO₂, H₂O).

• The composition of a binary compound dictates its name.

• Binary compounds are widely used in daily life (e.g., water, table salt, carbon dioxide).

• The chemical formula for a binary compound can be determined by considering the valencies of the ions of which it is made. Once the chemical formula is established the compound can be named and is derived from the names of the two constituent ions.

What is a chemical element?

Figure 2.1: Some common elements

Activity 1:

What you need: pen/pencil, exercise book What to do: Work alone or with up to 5 friends.

1. Identify five other elements apart from the ones in the picture above that you are familiar with.

2. Make a list of five items each found in your school and home and identify the elements they are made up of.

3. What is an element and how many do you know? Note – answer in Annex 1.

The Periodic Table

Figure 2.2: Periodic Table of elements.

The picture above shows a period table of elements. Take some time and carefully examine it.

The Periodic Table helps scientists to classify elements based on their chemical and physical properties into metals, non-metals, and semi-metals.

Elements in the same vertical column, is known as a group. “They share similar chemical properties because they have the same number of valence electrons.”

(“What are the vertical columns of a periodic table called?”) Valence electrons are the electrons in the outermost shell (energy level) of an atom. Elements in the same horizontal row, known as a period, have the same number of shells (principal energy level) but different numbers of valence electrons. As you move across a period (from left to right or vice versa) the properties of elements change gradually. Tell your friend what this changes are.

Hello learner, it is time for an activity!

Activity 2

Scenario: Imagine you’re a scientist carrying out a research in a laboratory.

Your task is to study the properties and characteristics of the first 30 elements in the Periodic Table. You have access to various samples of these elements and state-of-the-art equipment to analyse them.

What you need: periodic table, pen/pencil, exercise book, ruler What to do: Work alone or in a mixed group of not more than five learners.

Task:

1. What are the atomic numbers and symbols of the first 30 elements?

2. Identify the groups and periods to which each element belongs.

3. Examine the common properties shared by elements within the same group.

4. How do the properties of elements change as you move across a period?

5. Classify each element as a metal, non-metal, or metalloid based on its properties?

6. Identify some everyday uses of these elements.

Groups 1, 2 and 7

Group 1 elements known as alkali metals share similar properties such as high reactivity due to having one valence electron. They are so called because they react violently with water to form strong soluble bases. They are very soft and silver-like lustre. Using the periodic table find out more about them.

Group 2 elements known as alkaline earth metals have two valence electrons and are highly reactive but less reactive than alkali metals. They have a gray- white lustre when freshly cut but tarnish readily in air, Group 7 elements also known as halogens (meaning salt makers) are highly reactive non-metals with seven valence electrons. At room temperature and atmospheric pressure the halogens in their free states exist as diatomic molecules. Research the definition of the term ‘diatomic’.

The semi-metals are found in the middle of the periodic table. They have varying numbers of valence electrons and exhibit a wide range of chemical behaviours.

Periodic Table: Fast Facts

• The Periodic Table is a graphical collection of element data.

• The table lists the chemical elements in order of increasing atomic number, which is the number of protons in an atom of an element.

• The rows (periods) and columns (groups) organize elements according to similar properties. For example, all of the elements in the first column are reactive metals that have a valence of +1.

• All elements in a row have the same outermost electron shell.

Welcome to the fascinating world of elements, which are broadly categorised into three distinct groups: metals, non-metals, and semi-metals (metalloids).

Imagine a bustling marketplace where each element sets up its own stall, showcasing its identity and attractiveness. Picture gleaming metals catching the sunlight, sturdy and dependable. Contrast that with the subtle elegance of non- metals, with their diverse forms and functions. And then there are the puzzling semi-metals, straddling the line between two worlds, embodying the best of both.

Metals Metals, the true rock stars of the elemental world, comprise roughly about 70% of known elements located on the left-hand side of the periodic table. They are elements that donate electrons in a chemical reaction to form cations. Eg. Li, Na, K, Be, Mg and Ca.

Lead Gold Silver Copper

Figure 2.3: Some common metals They dazzle us with their thermal and electrical conductivity, malleability, ductility and strength. From the gold and silver in our jewellery to the stainless steel utensils in our kitchens, metals shape our world with their resilience and versatility.

Physical properties of metals

1. Metals are solids at room temperature except mercury and gallium which are liquids at room temperature.

2. Metals are lustrous. They have the quality of reflecting light from its surface and can be polished e.g. gold, silver, and copper.

3. Metals are malleable. They have the ability to be beaten into different shapes without breaking into pieces.

4. Metals are ductile. They can be drawn into flexible wires.

5. All solid metals are hard except alkali metals (sodium, rubidium, caesium, lithium, and potassium) which are soft and can be cut with a knife.

6. Metals have 1 to 3 electrons in the outermost shell of their atoms. They form cations by donating the electrons in their valence shells.

7. Metals are good conductors of heat and electricity because they have free electrons. Silver and copper are the two best conductors of heat and electricity. Lead is the poorest conductor of heat. Bismuth, mercury, and iron are also poor conductors.

8. Metals are very heavy and have high densities. Iridium and osmium have the highest densities while lithium has the lowest.

9. Metals have high melting and boiling points.

10. Some metals are sonorous (they produce a sharp ringing sound when hit by an object.)

Very good learners, You will do an activity!

Activity 3:

Scenario: Imagine you’re a budding scientist working in a laboratory, eager to explore the fascinating world of thermal conductivity in metals. Your task is to design and conduct an experiment that demonstrates how different metals conduct heat.

Aim: To investigate the thermal conduction properties of a selection of metals.

What you need: source of heat (e.g.. Bunsen burner, coal pot), Vaseline or Shea butter, copper, iron, brass, and aluminium rods (you can use stainless steel in place of brass rods. You can also get the metals from household items such as canned drinks, iron nails, copper wire. Ensure that the sizes of rods/ strips used are the same.) stopwatch, drawing pins, tripod stand, cardboard or paper, matches.

What to do:

1. Stick the flat end of a drawing pin to the end of each metal rod using the Vaseline/shea butter. Try to use the same amount for each drawing pin.

2. Place the cardboard on the tripod (this insulates the metal rod from the metal tripod).

3. Balance the metal rods on the cardboard so that one end is over the Bunsen burner but not too close that it catches fire.

4. Light the Bunsen burner.

5. Using a stopwatch, time how long until each pin drops off.

6. Record your results in a table.

Figure 2.4: Experimental set-up for thermal conductivity of metals.

Results and recording: Record your results in the following table Type of metal Time taken for pin to drop off (seconds) Iron Copper Brass Aluminium Write down your observations and conclusions.

Key Questions:

1. Which metals exhibited the fastest temperature increase along their length, indicating higher thermal conductivity?

2. How did the rate of temperature change vary between different metals?

3. Were there any observable differences in thermal conductivity among metals with similar physical properties?

4. How did the thickness or surface area of the metal samples affect their thermal conductivity?

5. What real-world applications or implications does the observed variation in thermal conductivity have for different metals?

6. How would you modify the experiment to investigate additional factors influencing thermal conductivity, such as temperature gradients or surface treatments?

Hope you enjoyed the experiment. Great, let us do another one!

Activity 4:

Scenario: Imagine you are a metal specialist conducting an experiment to demonstrate the malleability of metals. Malleability refers to the ability of a material to deform under pressure without breaking, allowing it to be shaped into various forms. Your task is to design and conduct an experiment that investigates the malleability of metal Aim: to investigate the malleability of different metals by striking them with a hammer.

What you needed: Pieces of iron, zinc, lead, and copper, hammer, an anvil, or solid block of iron to act as an anvil. You can also include a non-metallic control sample for comparison, such as plastic or ceramic.

Task:

1. Note the initial shape and measurement of each piece of metal.

2. Take a piece of iron and place it on the block of iron or anvil.

3. Strike the piece of iron five times with a hammer.

4. Observe and record any changes in the shape of the piece of iron.

5. Repeat the same process with pieces of zinc, lead, and copper.

6. Conduct multiple trials for each metal sample to ensure consistency and reliability of results. Take measurements and observations at regular intervals during each trial.

7. Record observations and note any differences in how each metal changes shape.

8. Repeat the experiment using a non-metallic control sample (e.g., plastic or ceramic) to compare its behaviour under pressure with that of the metal samples.

Write down your observations and conclusions.

Figure 2.5: Striking an iron nail with a hammer.

Key Questions:

1. Which metals exhibited the greatest degree of deformation under pressure, indicating higher malleability?

2. How did the amount of pressure required to deform each metal sample compare to its malleability?

3. Were there any observable differences in the behaviour of metals with similar physical properties, such as density or atomic structure?

4. Did the control sample (non-metallic) exhibit similar deformation characteristics under pressure, or was there a noticeable difference compared to the metal samples?

5. How does the malleability of metals contribute to their usefulness in various applications, such as metalworking, construction, or manufacturing?

6. How would you modify the experiment to investigate additional factors influencing the malleability of metals, such as temperature or alloy composition?

Observation: Metals have varying degrees of malleability and there should be a range of deformations amongst the four metals being investigated here:

copper and lead are more malleable than zinc or iron.

Conclusion: metals can be hammered into different shapes.

Hello learner, how was that activity? Interesting, isn’t it? Good. You will continue with the next activity.

Activity 5:

Scenario: Imagine you are an architect conducting an experiment to showcase the lustrous nature of metals for a big project. The lustre of a material refers to its ability to reflect light, resulting in a shiny or glossy appearance. Design and conduct an experiment to help you select lustrous metals for your project.

Aim: To compare the lustre of different metals.

What you need: Samples of iron, copper, aluminium, gold, silver and sandpaper. Plastic, ceramic, wood. Ensure that the samples are clean and free from tarnish or corrosion. A bright light source, such as a lamp or flashlight, to provide uniform illumination for the experiment. A dark non-reflective surface to be used for the testing.

What to do:

1. Observe and note the appearance of each metal sample under normal ambient lighting conditions. Note any inherent lustre or shine present on the surface of the metals.

2. Clean the surface of each sample by rubbing it with sandpaper.

3. Position the light source at an angle relative to the metal samples, ensuring that the light reflects off the surface of the metals.

4. Observe and note any changes in appearance of the samples.

5. Repeat the experiment using non-metallic materials, such as plastics, ceramics, or wood, as control samples. Note any differences in the appearance and reflectivity of the non-metallic materials compared to the metals.

Write down your observations and conclusions.

Key Questions:

1. Which metals exhibited the most pronounced lustre or shine when exposed to direct light, and why?

2. Were there any noticeable differences in lustre among metals with similar physical properties, such as density or atomic structure?

3. Did the non-metallic control samples exhibit any lustre or reflective properties similar to the metals, or was there a distinct difference in appearance?

4. How does the lustrous nature of metals contribute to their aesthetic appeal and value in various applications, such as jewellery, architecture, or decorative arts?

5. How would you modify the experiment to investigate additional factors influencing the lustre of metals, such as surface finish, alloy composition, or surface treatment?

Good job learners. Now let us explore on the hardness of metals in the next

activity.

Activity 6:

Scenario: Imagine you are a materials scientist tasked with conducting an experiment to demonstrate the hardness of metals. Hardness refers to a material’s ability to withstand deformation, indentation, or scratching when subjected to external forces. Design and conduct your experiment.

Aim: To demonstrate the hardness of metals compared with other non-metal materials What you need: Various objects made of varied materials (e.g., metal spoon, key, rubber band, plastic ruler, piece of cloth, wood), a coin.

What to do:

1. Place each metal sample on the testing surface and position the hardness testing device directly above it (in this experiment you can use a coin).

Apply a controlled force to the surface of the metal sample using the coin, ensuring uniform pressure across the entire surface. Try to scratch the surface of each object with the coin.

2. Record your observations.

3. Repeat the experiment using non-metallic control samples, such as plastics, ceramics, or wood, to compare their hardness properties with those of the metal samples.

Write down your observations and conclusions. Try to explain these using your scientific knowledge of metals.

Key Questions:

1. Which metals exhibited the highest resistance to indentation or deformation when subjected to the applied force, indicating greater hardness?

2. How did the observations obtained for each metal sample compare to their known hardness ratings or properties?

3. Were there any noticeable differences in hardness among metals with similar physical properties, such as density or atomic structure?

4. Did the non-metallic control samples exhibit similar hardness properties to the metals, or was there a distinct difference in resistance to deformation?

5. How does the hardness of metals influence their suitability for specific applications, such as cutting tools, machinery components, or structural materials?

How would you modify the experiment to investigate additional factors influencing the hardness of metals, such as alloy composition, heat treatment, or surface finish?

Well done learner! Let us take a dive into the chemical properties of metals.

Chemical Properties of Metals

Reactivity: This is the ability of metals to undergo chemical reactions with oxygen, water or acids. Metals vary in their reactivity with oxygen, water or acids. Some metals, like zinc and aluminium, react with acids to produce hydrogen gas and a metal salt. Others are resistant to reaction. Some metals are more reactive than others and can be ordered into a reactivity series from most to least reactive (e.g., Mg, Al, Zn, Fe, Sn) Let us do an activity!

Activity 7:

Scenario: Assume you are a chemist tasked with creating a metal reactivity series to predict the relative reactivity of different metals. Design and conduct your experiments to verify the reactivity series of samples of metals.

Aim: To show the reaction of metals with acids.

What you need: sample metals e.g., magnesium, zinc, iron, copper, and lead, test tubes, dilute HCl, test tube rack, matches or splint What to do:

1. Obtain samples of several metals, including magnesium, zinc, iron, copper, and lead.

2. Prepare and label test tubes containing solutions of dilute hydrochloric acid.

3. Place small pieces of each metal into a labelled test tube and observe the reactions.

4. Record your observations, noting any effervescence (formation of bubbles), colour changes, or the release of gas.

5. Test bubbles with a flaming splint and observe a pop sound.

6. Based on your observations, arrange the metals in order of decreasing reactivity, creating a metal reactivity series.

Write down your observations and conclusions.

Hello learner, well done with the experiment. Let us turn our attention now to corrosion.

What is corrosion?

Figure 2.6: metal parts under going rusting Look at the picture above and write your observations. You may discuss with your friends. If you work in groups, the should not be more than 5 members. Cite examples of similar situations in your environment and discuss with your group.

Corrosion Many metals undergo corrosion. It is a chemical reaction with substances in the environment that leads to the deterioration of the metal. Iron, for example, corrodes to form rust in the presence of oxygen and water.

Corrosion is a natural chemical process (oxidation) that occurs when a metal reacts with oxygen/air in the presence of water to form an oxide. Rusting refers specifically to the corrosion of iron or steel (an alloy of iron). Other metals such as aluminium can also corrode.

Formation of Alloys

Metals can form alloys which are mixtures of two or more metals or a metal and a non-metal. Alloying often enhances the properties of metals such as increased strength or resistance to corrosion.

Hello learners, you will explore the uses of metals!

Uses of metals

• Gold, silver, platinum, and copper are widely used in jewellery.

• Iron and steel (an alloy of iron) are widely used in building and home construction.

• Cooking utensils are best made from metals like steel, aluminium, and copper.

• Sodium (Na), potassium (K), magnesium (Mg), and many others are available as micro-nutrients in our body.

• Iron, steel, titanium and aluminium are used in machinery and auto-mobile construction.

Dear learner, surf the internet to find three further examples of the uses of metals.

Activity 8:

Scenario: Imagine you are a Chemist studying the corrosion of iron in different environmental conditions. Design and conduct an experiment to investigate the corrosion of iron.

Aim: To demonstrate the conditions necessary for rusting of iron What you need: Test tubes, iron nails, cork, distilled water, oil, Anhydrous calcium chloride.

What to do:

1. Take three test tubes and place clean iron nails in each

2. Label these A, B, and C.

3. Pour some water into a test tube A and cork it. The water should cover the nails.

4. Pour enough previously boiled and cooled water into test tube B to cover the nails, add about 1 ml of oil and cork it. The oil will float on water and prevent the oxygen from dissolving into the water. Boiling removes dissolved oxygen from the water.

5. Put approximately 5g of anhydrous calcium chloride in test tube C and cork it. Anhydrous calcium chloride will absorb any moisture from the air.

6. Leave the test tubes for a week and then observe and note the results.

Write down your observations and conclusions.

Figure 2.7: laboratory set-up for rusting experiment https://www.youtube.com/watch?v=XMr4vse7Ybo Key Questions

1. What was the role of the oil in test tube B?

2. How can you relate the oil in test tube B to the use of oil based paints on iron or steel based materials exposed to harsh weather conditions?

3. What are the mechanisms by which environmental conditions promote corrosion?

Great work done my dear learner. End the activity by researching the following ways in which the rusting of metals can be prevented:

1. Painting

2. Clear Coats and Sealants coating

3. Galvanising

4. Plating

5. Alloying

6. Keeping the metal in cool dry place

7. Desiccants

8. Let us explore the corrosion of iron a bit deeper.

9. Corrosion of Iron (Rusting)

Welcome learner, do you remember what you read about corrosion of metals? Yes, corrosion is said to happen when metals deteriorate due to a reaction between the metal and chemical elements within its environment. Corrosion in other metals are referred to as tarnish. However, corrosion in iron is referred to as rust.

Let us explore the chemical process of rust.

The chemical reaction involved in rusting can be represented as follows:

Iron (Fe) + Oxygen (O₂) + Water (H₂O) →Hydrated Iron (III) Oxide (Rust) 4Fe + 3O₂+ 2H₂O → 2Fe₂0₃.H₂O From the chemical equation, Conditions necessary for rusting to occur are:

1. Water (moisture)

2. Air (oxygen) Rust is a reddish-brown coating that forms on the surface of the iron. It weakens the metal over time, causing it to deteriorate and lose its structural integrity. This process can be accelerated in warm, salt-water, or acidic conditions.

Non- Metals

Non-metals, from the essential oxygen we breathe to the vibrant carbon in all living things, play crucial roles in the chemistry of life and the environment.

Non-metals are chemical elements that do not have the properties of a metal for

example, Hydrogen (H), Helium (He), Carbon (C), Nitrogen (N), Oxygen (O).

they are found on the right-hand side of the Periodic Table. They accept electrons from metals in a chemical reaction to become anions. They also share valence electrons to form covalent bonds.

Physical properties of Non-metals

1. Physical state: Most non-metals exist in two of the three states of matter at room temperature: gases such as oxygen and solids such as carbon.

2. Low Ductility: Non-metals are usually very brittle and cannot be rolled into wires or pounded into sheets.

3. Poor conductivity: Non-metals are typically poor conductors of electricity and heat. However, graphite (a form of carbon) is a notable exception.

4. Poor lustre: Non-metals often have dull, non-reflective surfaces.

5. Low malleability: Solid non-metals cannot be easily hammered or pressed into different shapes without fracturing.

Chemical Properties

1. Reactivity: They form acidic or neutral oxides with oxygen. Non-metals tend to gain electrons in chemical reactions, making them reactive towards metals.

2. Electronegativity: They have higher electronegativity compared to metals, meaning they attract electrons more strongly.

3. Ionization: Non-metals easily gain electrons to form negative ions (anions) or share electrons to form covalent bonds.

4. Acidity: Many non-metals form acidic oxides when they react with oxygen, such as sulphur dioxide (SO₂) and carbon dioxide (CO₂).

5. Hydrogen Bonding: Non-metals like oxygen and nitrogen exhibit hydrogen bonding, influencing their properties in compounds.

Well done learners, let us explore the uses of non-metals. Great!

Uses of Non-metals.

• Nitrogen can be used as a food preservative and in light bulbs. Nitrogen and phosphorus are used in fertilizers to help plants grow. Nitrogen and phosphorus are used in fertilizers to help plants grow.

• Sulphur is used in making black gunpowder, matches, and fireworks. Sulphur is used to vulcanize rubber.

• Chlorine can be used as a bleaching agent and in the treatment of water to make it safe to drink.

• Hydrogen fuel cells generate electricity from oxygen and hydrogen.

• Oxygen used in space rockets as fuel, in respiration, in welding.

• Iodine is used as an antiseptic in a purple solution on wounds.

• Carbon in the form of Charcoal is used in the sugar industry for decolorization.

Graphite another form of carbon is used to make pencil leads.

• Other materials: Non-metals are used to make gunpowder, fireworks, matches, rubber, cement, ceramics, glass, and lime products.

Well done my dear learner. Let us explore semi-metals.

Semi-Metals (Sometimes called Metalloids) What are semi-metals?

Semi-metals are elements found along the “staircase” line in the periodic table, bordering the region between metals and non-metals. The semi-metals include boron, silicon, germanium, arsenic, antimony, and tellurium.

Semi-metals show some properties of both metals and non-metals making their classification intermediate between the two groups.

Properties of semi-metals Conductivity of electricity: Partial conductivity - better than non-metals but not as good as metals.

Malleability: Intermediate between metals and non-metals Ductility: Also intermediate between metals and non-metals.

State: All semi-metals are solid at room temperature Look at the picture below carefully. You may work alone or with friends in a group. Use the internet to search more about the characteristics of each of the elements.

Figure 2.8: semi-metals Differences Between Metals and Non-Metals The classification of solids into metals, non-metals, and semi-metals helps in understanding the fundamental properties and behaviours of different elements, and it provides a foundation for studying their various chemical interactions and applications.

Find in the Table 1 below differences between metals and non-metals

Table 1: Differences between metals and non-metals Metals Non-metals Metals are good conductors of electricity due to the mobility of their valence electrons that can move freely within the metal.

Non-metals are typically poor conductors of electricity because their valence electrons are tightly held and do not move as freely.

Metals are higher conductors of heat, allowing heat to be transferred quickly through the material.

Non-metals have lower heat conductivity, so they are less efficient at conducting heat.

Many metals have a shiny appearance or lustre when freshly cut or polished.

Non-metals lack lustre and appear dull in their natural state.

Metals are malleable and can be hammered or pressed into various shapes without breaking.

Non-metals are brittle and cannot be easily hammered.

Metals are ductile and can be drawn into thin wires without fracturing.

Non-metals cannot be drawn into wires without breaking.

Differences between semi-metals and non-metals

Table 2: Differences between semi-metals and non-metals.

Semi-metals Non-metals

They may be brittle like non-metals and have intermediate malleability and ductility.

They are typically brittle in solid form.

Semi-metals often have intermediate thermal conductivity.

They have low thermal conductivity making them good insulators in most cases.

Semi-metals have intermediate electrical conductivity.

They are bad conductors of electricity.

Differences Between Metals and Semi-Metals

Table 3: Differences between metals and semi-metals.

Metals Semi-metals

Are excellent conductors of electricity.

Have intermediate electrical conductivity.

Metals have high heat conductivity. Have intermediate heat conductivity.

Metals are often malleable and ductile.

Semi-metals can be brittle, making them less suitable for applications where malleability and ductility are important.

Metals tend to be reactive. Semi-metals have intermediate reactivity.

Metals typically have a shiny, metallic lustre due to the reflection of light from their surface.

Semi-metals may have a metallic appearance but can also appear dull or non-metallic.

Activity 9

Create a poster summarising your understanding of the classification of metals, non-metals and semi-metals.

Activity 1

An element is a pure chemical substance that cannot be broken down or changed into another substance by chemical means. It is made up of only one kind of atom. They are thought of as basic building blocks for everything around us, whether solids, liquids or gases. Some examples of elements are hydrogen (H), carbon (C), oxygen (O), fluorine (F) and calcium (Ca). Elements are represented by symbols (like those in the brackets) and fit into the Periodic

Table of elements, which shows them all. There are 118 elements on the periodic table, with 94 of them occurring naturally. The rest are synthetic elements that have been created in a laboratory.

Activity 3

Observation: The pin stuck to the copper rod should drop off first as copper is the best conductor of heat and the Vaseline will melt first.

Conclusion: Metals vary in their thermal conductivity with copper having the best in this selection.

Activity 4

Observation: Metals have varying degrees of malleability and there should be a range of deformations amongst the four metals being investigated here:

copper and lead are more malleable than zinc or iron.

Conclusion: Metals can be hammered into different shapes.

Activity 5

Observation: Silver and gold shine the most (are the most lustrous) than other metals such as copper, iron and aluminium.

Conclusion: Metals exhibit a shining surface known as metallic lustre, the degree of lustre varies amongst metals.

Activity 6

Observe: You should have noted which objects resist scratching and which ones are easily scratched by the coin.

Conclusion: The metal objects should be difficult to scratch, whilst the softer materials should show visible scratches indicating that they are less hard.

Explanation: Metals are harder than other materials because their atoms are arranged in strong, ordered structures. This makes it difficult to deform or break the metal’s surface when scratched. Softer materials have weaker atomic bonds, making them more susceptible to scratches and dents.

Activity 7

Observation: effervescence will be observed in each of the test tubes with the most reactive showing more and rapid release of bubbles and the least reactive showing slow and least release of bubbles.

Conclusion: the metals arranged from the most to the least reactive metal are magnesium, zinc, iron, lead and copper.

Activity 8

Observation: Iron nails will rust in test tube A but they should not rust in test tubes B and C. In test tube A, the nails are exposed to both oxygen and water.

In test tube B, the nails are exposed to only water, and the nails in test tube C are exposed to only to oxygen.

Conclusion: Oxygen (in air) and water are required for rusting to take place.

Methods for the prevention of corrosion include:

1. Painting: Paint provides a protective layer that seals the metal surface and blocks moisture and oxygen from reaching the metal.

2. Clear Coats and Sealants coating: Transparent coatings like lacquers and clear sealants can be used to protect metal surfaces while preserving their natural appearance.

3. Galvanising: Galvanising involves electro-coating the iron (or steel) with a thin layer of zinc. This has two modes of protection - the thin layer of zinc acts as a barrier to water and oxygen; and zinc is more reactive than iron and corrodes instead of the iron (called sacrificial protection).

4. Plating: Plating involves depositing a layer of another metal onto the surface of the base metal. This outer layer serves as a protective barrier. For

example, chrome plating is commonly used for decorative and corrosion- resistant purposes.

5. Alloying: Alloying involves mixing two or more different metals or non- metal and a metal. This helps to improve its corrosion resistance. An example of this is stainless steel which contains chromium which reacts with oxygen to form a thin, invisible oxide layer on the metal’s surface. This layer acts as a barrier, protecting the underlying metal from rust.

6. Keeping the metal in cool dry place: Keeping metal objects dry and clean reduces the likelihood of corrosion.

7. Desiccants: The use of moisture-absorbing substances like silica gel packets or other desiccants when storing metal objects in enclosed spaces can reduce corrosion and is used in many commercial products within the packaging.

From your previous discussions, you classified solids as either metal, non-metal or metalloid (semi-metals). Unlike liquids and gases, which can flow and change shape easily, solids maintain their shape and volume under normal conditions.

As mentioned earlier, solids are characterised by intermolecular forces which are greater in magnitude than the energy of the individual particles. These forces hold their constituent particles such as atoms, ions, or molecules in a fixed arrangement.

Activity 10

A) In a mixed group with no more than 3 other members of your class, sort the following materials into metallic and non-metallic groups. As an extension think about how each of these materials would be used in the construction of a house:

Materials:

• Concrete

• Aluminium

• Wood

• Zinc

• Plastic

• Iron

• Copper

• Glass B) Now discuss and list materials that are used or needed in constructing the following items and form concept map for each – glassware, vehicles, computers, bottles, bowls, tables, sculptures and bridges. Generate a concept map (similar to the example solution to Activity 10 part A, found in Annex 2.2) for each.

Solids can be sub-categorised into the following groups which share similar properties:

• Polymers

• Crystalline structures

• Metals

• Fibrous materials

Table 4: Classification of materials Classification Examples of solids Reason(s) Polymers Polyethylene, polyvinyl chloride (PVC)

• They are large molecules made up of repeating subunits called monomers

• They are flexible and have a high strength-to-weight ratio

• Low conductivity of electricity and heat Crystalline Table salt, sugar (sucrose), diamond, quartz

• Exhibit well-defined geometric shapes

• They have a highly ordered and repeating arrangement of particles (crystals)

• High melting point Fibrous material Wood • Flexible

• They do not form crystals

• Low conductivity of electricity and heat Metal Copper • Conducts electricity

• High melting point

• Good thermal conductivity From Table 4, some solids have been sampled and classified. Now discuss with your friends the reasons assigned to each classification.

Properties of solid metals and some of their uses Study the following properties of solid metals as captured in the Table 5 and see how it applies to everyday use.

Table 5: Properties of solid metals and some of their uses Property Examples use(s) Conductivity: A high conductivity allow fast movement of heat and/or electricity.

This property is valuable in electrical wiring, power transmission, electronics, and heating.

Magnetic properties: Iron, nickel, and cobalt exhibit magnetic properties. This means they will exhibit a force on each other when brought into one another’s magnetic fields.

This characteristic or property is essential for electrical motors, generators, transformers, and magnetic storage devices.

Lustre/Reflectivity: Solids

which often have a smooth surface and have high reflectivity for light and heat.

This property is used in applications such as mirrors, reflectors, and solar panels where efficient reflection is required.

High melting and boiling points: Most metals have high melting and boiling points allowing them to withstand high temperatures (mercury is the exception to this rule as it is a liquid at room temperature).

Metals with extremely high melting points, such as tungsten and molybdenum, produce refractory materials capable of withstanding very high temperatures.

Metals with high melting points are used to make crucibles and moulds for casting other materials such as ceramics and alloys. The crucible or mould remains stable and doesn’t deform during casting.

Other metals (such as lead) with lower melting points are used in soldering and brazing processes to join different components.

Property Examples use(s) Density: The density of metals refers to how much mass is packed into a given volume of the material.

In military and defence applications, high-density metals like depleted uranium are used in armour-piercing ammunition due to their ability to penetrate heavily armoured targets.

Understanding the density of metals is crucial for recycling and waste management. By identifying and sorting metals based on their densities, recycling facilities can efficiently separate and process different metals for reuse, reducing the environmental impact of metal production.

Having discussed the properties of solid metals and how they are used in everyday life, I want you and your group members to try the following experiments to prove the realities of these properties.

Activity 11:

(You can do this activity alone or in a group of 2-4 classmates) Aim: To compare the magnetic properties of various materials.

Materials needed: Bar magnet, iron nail, copper wire, aluminium foil, coin, paper clips, plastic ruler, wooden stick, plastic bottle cap, Styrofoam ball and rubber band.

Task

a) Position the bar magnet on a level surface.

b) In turn, bring each of the other pieces of equipment close to the bar magnet one at a time to see if there is any attraction or repulsion between them.

c) Classify each object as magnetic or non-magnetic and list these in a

table.

Observations What are your observations? Discuss it with your friends and compare them with the observations and conclusions in Annex 2.2.

Extension task:

Think of some activities where magnetism would be beneficial, as well as some where magnetism would be detrimental. Outline in a few sentences why magnetism can be useful or not for use in the applications you have chosen.

Activity 12:

(You can do this activity alone or in a group of 2-4 classmates) Aim: To investigate the densities of different solid materials.

Materials needed: Various metal samples such as iron (e.g., nail, iron rod piece), lead (e.g., lead from electronic shops), aluminium (e.g., canned drink containers), copper (e.g., copper wires from electrical wires), zinc (e.g., battery case or disposed zinc roofing sheet), balance, measuring cylinder, beaker, water, forceps, scale.

Task:

a) Start by collecting samples of the metals you want to test. Make sure they are clean and free of any dirt or debris.

b) Weigh the mass of each metal sample and record in grams.

c) Fill the measuring cylinder with a known volume of water and record.

d) Carefully lower the first metal sample into the water using a pair of forceps. Make sure the metal is fully submerged.

e) Measure and record the new increased in volume of water after adding the metal sample. Measure volume in ml/cm3 (1 ml = 1cm3).

f) Repeat for each metal sample.

g) Calculate the volume of each metal sample by subtracting the initial volume of water from the final volume of water.

h) Use the formula: Density = Mass / Volume to calculate the density of each metal sample.

i) Record your results and compare the densities of the different metals.

Fig. 2.9: illustrates how the volume of the metals are determined Observations: What are your observations? Discuss it with your friends and compare them with the observations and conclusions in Annex 2.2.

Activity 13:

Aim: To investigate the electrical conductivity of different solid materials.

Materials needed: Solid objects composed of a range of materials e.g., metal rod, key, wooden stick, plastic ruler, graphite rod, pencil, etc., battery, LED bulb and wires. Be guided by the image in Figure 2.10

Figure 2.10: activity to show which materials are good conductors of electricity Task:

a) For each material you are going to test; predict whether or not they will conduct electricity. Make a note of your predictions, justifying them with a reason.

b) Construct a simple circuit set-up with a battery, LED bulb, and wires.

c) Check if the circuit conducts electricity, the battery is functioning, and the bulb is working by connecting the free wire ends to complete the circuit. If the bulb lights, the circuit is working.

d) One by one, introduce the metal rod, wooden stick, plastic ruler, graphite rod, and pencil lead into the circuit to complete it.

Note: the pencil lead is in fact graphite, ensure the wires are connected to the lead of the pencil rather than the surrounding wood.

e) Does the bulb light up? Record your results in a suitable table and write a suitable set of conclusions to your experiment. Remember to refer back to your predictions.

Observations: What are your observations? Discuss it with your friends and compare them with the observations and conclusions in Annex 2.2.

Activity 14

Your group should create a poster or oral presentation to demonstrate your findings from the three experiments outlined above, considering how you can make your presentation of most interest to an

Activity 10

A)

Example answer:

B) Structures Examples of solids used in the structures Building Concrete, Steel, wood, brick.

Glassware Sand is a raw material in the making of glass, glass wool, glass beads.

Vehicle Metals, glass, plastics, leather, cushion, connecting wires.

Gadgets (e.g., computer) Glass, plastics, Copper, metals, etc.

Plastic materials (e.g., bottles, bowls) Polyethylene, Polyvinyl Chloride (PVC).

Table Wood, nails, Steel, plastic, glass.

Sculptures Stones, marble, metal, or wood.

Bridges Steel, concrete, stone.

Activity 11

Observation From this activity, you are likely to observe that:

• Materials such as the iron nail, paper clips, and copper wire will be attracted to the magnet, showing magnetic properties.

• Materials like the aluminium foil, plastic ruler, wooden stick, plastic bottle cap, styrofoam ball, and rubber band will not be attracted to the magnet and are considered non-magnetic.

Conclusion: You will now come to the realisation that certain materials exhibit magnetic properties and are attracted to a magnet whilst others do not show any magnetic response.

Activity 12

Observations: From the activity, you will observe that different metals will have different densities.

Conclusion: Metals vary in density and have different uses e.g. Lead is often used in adding ballast (weight) as it is very dense and therefore heavy for its volume. Aluminium is one of the less dense metals and is often used in applications which require low weight such as spaceflight or aviation.

Activity 13

Observations: You will observe that the metal rod, pencil lead and graphite rod will all conduct electricity (the bulb lights up) and the wooden stick and plastic ruler will not.

Annex 2.2 – Further Information Uses of Polymers in relation to their properties Read the table below to identify how the properties of polymers are used in everyday life.

Table 6: Properties and example uses of polymers Property Polymer(s) exhibiting this property Use(s) Strength (ability to withstand load without deformation) and Durability (resistance to wear) Polyethylene (PE) and Polypropylene (PP) Polyvinyl Chloride (PVC) Aramid fibres Packaging Pipe work Bulletproof vests Flexibility and Elasticity (ability to bend and stretch without breaking) Rubber Elastic bands Thermal Stability Polyimides (PI) Aerospace Chemical Resistance (resistance to acids, corrosion or solvents) Polyvinylidene fluoride (PVDF) Polytetrafluoroethylene (PTFE) Storage tanks Pipework Electrical Insulation Polyethene (PE) and Polypropylene (PP) Cable insulation Transparency Polymethyl methacrylate (acrylic) Lenses Water Resistance Polyethylene terephthalate (PET) Water bottles Biodegradability (can be degraded naturally by decomposers and environmental processes over time) Polylactide (PLA) Compost bags Adhesive Cyanoacrylate Glue The properties and uses of crystalline solids (e.g. glass)

Table 7 shows the properties of different types of glass and its everyday uses.

Table 7: The properties and uses of crystalline solids Glass Properties Use Soda-lime glass Transparent Chemical resistance - it is non-reactive Soda-lime glass has a moderate coefficient of thermal expansion meaning it expands and contracts evenly when exposed to temperature changes Windows, bottles, and jars and scientific glassware Borosilicate Exhibits high chemical resistance High thermal resistance Durability Laboratory glassware, chemical storage containers, and pharmaceutical packaging where the material needs to withstand corrosive substances. Also, cookware e.g., Pyrex and high-end lighting fixtures.

Lead crystal It contains a significant amount of lead oxide giving it exceptional clarity, brilliance, luxurious appearance, and weight.

Fine glassware, chandeliers, and decorative items.

Glass Properties Use

Fused silica Its high purity, thermal stability, optical transparency, and chemical resistance makes fused silica is a versatile material used in a wide range of industries Lenses, mirrors, and precision optics in scientific instruments.

Aluminosilicate glass Contains aluminium oxide and silica offering high strength, chemical resistance, and thermal shock resistance.

Smart phone screens, armoured vehicle windows, and aerospace components.

1. Properties of solid materials https://www.vaia.com/en-us/explanations/physics/solid-state-physics/ solids/

2. The property of materials and their everyday uses https://www.primaryresources.co.uk/science/pdfs/rsc_tc_nc1.pdf

3. Images of solid materials https://www.sciencelearn.org.nz/resources/2659-properties-of-materials- introduction

Figure 2.11: Table salt (NaCl) Figure 2.12 - Water (H₂O) Hello, learner. Think about the ingredients in your favourite dish! Like cooking, chemistry is all about combining the right elements in proportions to create something new and useful. Instead of using vegetables and fish, we use elements and valencies to form compounds. Just like in cooking, knowing the name of each ‘ingredient’ and how they come together is crucial. In this session, you will explore how two elements combine to form a binary compound, and how you can identify these compounds just like a chemist. You will also understand the logic behind their composition. Ready to solve some chemical mysteries? Let’s get started with an activity!

Activity 15

1. Define the following terms:

a) Element

b) Ion

c) Molecule

d) compound

2. Categorise the following into element, ion, molecule or compound (note, they could belong to more than one of these categories!

H2O, O₂, NaCl, Fe, Ca²⁺

Activity 16:

You are going to become a chemical detective and unlock the secrets of binary compounds. To start, let’s see if you can solve a few mysteries about some common compounds.

Materials needed: Periodic table, pen/pencil and exercise book.

What to do: You are provided with three clues. Carefully read each of the following clues and answer the questions:

a) What is the common name of this compound?

b) What two elements make up this compound?

Clue 1: “I am a white crystalline substance commonly found in kitchens. I am essential for flavouring food and preserving it.”

Clue 2: “I am a liquid that is vital for all known forms of life. I cover about 71% of the Earth’s surface.”

Clue 3: “I am a colourless gas. I am produced by burning fossil fuels. Plants need me for photosynthesis.”

Find the answers in Annex 2.3.

What is a binary compound?

A binary compound is a chemical compound composed of exactly two different elements. These elements combine in fixed ratios to form a new substance with unique properties.

Binary compounds are basic building blocks in chemistry. They can be classified into two main types based on the nature of the elements involved:

Binary Ionic Compounds

Composition: These compounds consist of a metal and a non-metal.

Formation: Metals lose electrons to become positively charged ions (cations), while non-metals gain electrons to become negatively charged ions (anions).

These oppositely charged ions attract each other to form an ionic bond. Thus, the metals transfer electrons to the non-metals to form the compound.

Example: Sodium chloride (NaCl), where sodium (Na) is a metal that loses one electron to become Na+, and chlorine (Cl) is a non-metal that gains one electron to become Cl–. The resulting compound is NaCl.

Let us learn how to draw the individual elements, followed by the bond that is formed in table salt (sodium chloride).

1. Draw the electron configuration of each atom in the compound (sodium and chlorine).

Figure 2.13:

2. Draw the electron configuration of the two ions after the transfer of electrons from sodium to chlorine, surround them with square brackets, and write the charge of each ion in the top right hand corner.

Fig. 2.14:

Figure 2.13 and 2.14 - Transfer of electron from Sodium to Chlorine resulting in Na+ and Cl- The electrostatic force of attraction between the two ions results in the formation of sodium chloride (NaCl).

This can be represented in another way:

Sodium atom (Na) loses an electron to become sodium ion (Na+) Na – e- -------> Na+ (2,8,1) (2, 8) Chlorine atom (Cl) accepts the electron from sodium to become chloride ion (Cl-) Cl + e- ---------> Cl- (2,8,7) (2,8,8) The electrostatic force of attraction between the two ions pulls them together to form a compound.

Na+ + Cl- ---------> NaCl

Activity 17

Scenario: You are a chemist tasked with identifying a newly discovered ionic compound composed of calcium and chlorine.

Question: How is the compound formed?

Materials needed: Periodic table, pens/pencils, exercise book What to do:

1. Use the periodic table to identify the elements.

2. Draw the electron configuration diagram of the elements.

3. Draw the electron configuration diagrams of the two ions after the transfer of electrons.

4. Write the formula of the compound formed.

5. Confirm your result with the solution in Annex 2.3.

Follow up questions:

Using the same method draw the electron configuration for the following atoms and then the ions they form when combined into compounds:

1. Fluorine and lithium

2. Beryllium and chlorine

3. Oxygen and calcium

4. Magnesium and iodine

5. Aluminium and fluorine

6. Gallium and oxygen.

Good job learner, now explore the properties of ionic compounds.

Properties of Ionic Compounds

Property Description

State of matter Most ionic compounds exist in a solid state at room temperature. The strong electrostatic forces between positively and negatively charged ions create a stable crystal lattice structure.

Melting and

boiling points Ionic compounds have high melting and boiling points.

The strong ionic bonds require a substantial amount of energy to break. High temperatures are needed for these compounds to undergo phase changes.

Solubility in

water Many ionic compounds are soluble in water. When placed in water, the ions separate and disperse throughout the solution. However, not all ionic compounds are equally soluble, and some may show limited solubility or are insoluble.

Conductivity in

aqueous solutions Ionic compounds conduct electricity when dissolved in water or in molten form. In these states, the ions are free to move and carry an electric current. However, in their solid state, ionic compounds do not conduct electricity and are good insulators.

Figure 2.15: In an ionic solution, the A+ ions migrate toward the negative electrode, while the B− ions migrate toward the positive electrode.

Crystal structure Ionic compounds form a regular and repeating three- dimensional crystal lattice structure. The arrangement of positive and negative ions in this structure contributes to the stability of the compound.

Figure 2.16 (a): Sodium

Chloride

Figure 2.16(b): Copper (II)

crystals Hardness and brittleness Ionic compounds are typically hard and brittle. The crystal lattice structure can fracture when subjected to force as like-charged ions repel each other.

Figure 2.17: (a) The

Sodium Chloride crystal is shown in two dimensions.

Figure 2.17(b): C(b) When struck by a hammer, the negatively charged. Chloride ions are forced near each other and the repulsive force causes the crystal to shatter.

Density Ionic compounds have high densities. The arrangement of ions in the crystal lattice contributes to the overall mass of the compound in each volume.

Colour Pure ionic compounds are often colourless. However, certain metal ions, especially transition metals, can impart colour to the compound. For example, Copper ions can give a blue or green colour to an ionic compound as seen in figure (2.16b).

Binary Covalent Compounds

Composition: These compounds consist of two non-metals.

Formation: Non-metals share electrons to form covalent bonds. This sharing allows each atom to attain a stable electron configuration.

Example: Carbon dioxide (CO₂), where carbon (C) shares electrons with two oxygen (O) atoms forming covalent bonds, water (H₂O), ammonia (NH₃) and methane (CH₄).

Figure 2.18: Examples of covalent compounds

Figure 2.19: the sharing of valence electrons to form a covalent bond Molecules such as hydrogen (H₂) and oxygen (O₂) also consist of covalent bonds.

In the formation of hydrogen gas, each of the two atoms of hydrogen contributes its electron to be shared with the other hydrogen atom. Sharing of electrons ensures that each hydrogen atom gains an additional electron in its valence shell.

This ensures that the shell has a stable configuration.

Figure 2.20: Formation of hydrogen gas (H₂) Similarly in a molecule of Oxygen Gas (O₂), the two atoms of Oxygen contribute a pair of electrons each to be shared. This ensures that each of the two atoms attains an inert configuration of 8 electrons in the valence shell.

Figure 2.2: Formation of oxygen gas (O2) Covalent bonds can be single, double or triple bond.

Activity 18:

Scenario: Imagine you are an environmental scientist studying the water cycle. To understand how water forms, you need to investigate the bonding between hydrogen and oxygen atoms to form water (H₂O). You are tasked to construct a model of water molecule.

Materials needed: Molecular model kits or play dough/plasticine/coloured clay/coloured polystyrene materials and toothpicks/broom sticks.

What to do:

1. Draw the electron configuration of H₂O on paper.

2. Ensure that each Hydrogen atom shares one electron with the Oxygen atom, forming two covalent bonds.

3. Select and use suitable materials to build a model of a water molecule, showing the sharing of electrons between Hydrogen and Oxygen.

4. Answer the following key questions:

Key Questions:

a) What is a covalent bond, and how does it differ from an ionic bond?

b) How do hydrogen and oxygen atoms share electrons to form a water molecule?

c) Why is water considered a binary covalent compound?

d) How do the shared electrons create a stable molecule.

Very good learner, compare your electron configuration diagram of water molecule to the one provided.

Compare your home-made water model to the one in the picture in Annex 1.

Properties of Covalent compounds Covalent compounds contain covalent bonds and exhibit the following properties:

• They normally exist as gases, liquid, or soft solids

• Their melting and boiling points are very low

• They can be insoluble in water but soluble in organic solvents

• They are non-conductors of electricity in solid, molten, or aqueous state

• They have weak intermolecular forces of attraction.

Activity 19:

Aim: To examine water’s electrical conductivity as a representative covalent compound.

Materials needed: Two electrodes (e.g., copper or graphite), electrical circuit with connecting wires, ammeter, switch, batteries, beaker and distilled water.

a) Set up an electrical circuit by connecting two electrodes to an ammeter, switch, and battery in series.

b) Fill a beaker with distilled water and place the electrodes into the water, ensuring they do not touch each other.

c) Observe and record changes in the ammeter reading as the electrodes are submerged in the water.

d) Repeat the experiment with other substances like salt (NaCl) dissolved in water and sugar (sucrose) dissolved in water.

Take safety precautions while conducting the experiment, such as wearing safety goggles, lab coats, and following standard laboratory practices.

Perform each test multiple times to ensure reliability of results.

Use distilled water to maintain consistency and reduce the influence of impurities on the experiment.

Observations: What are your observations? Discuss it with your friends and compare them with the observations and conclusions in Annex 1.

Activity 20:

Scenario: The Chemistry Detective

Imagine you are a detective in a forensics lab. You have been given two mysterious white powders found at a crime scene. Your job is to determine whether these powders are ionic or covalent compounds by investigating their properties through a series of tests.

Key Questions to answer before starting the investigation:

1. Physical properties of ionic and covalent compounds.

a) How do their melting points and boiling points differ?

b) How do their electrical conductivity and solubility in water differ?

2. Molecular structures of ionic and covalent compounds.

a) How do ionic compounds arrange their ions?

b) How do covalent compounds arrange their atoms?

3. How do ionic and covalent compounds behave when dissolved in water?

4. What happens to their electrical conductivity in aqueous solutions?

Activity 21:

Aim: To compare the properties of the given powders to determine whether they are ionic or covalent compounds.

Materials needed: Two white powders (e.g., NaCl (table salt) and C₁₂H₂₂O₁₁ (sugar)), distilled water, multimeter, beakers or clear cups, stirring rods, hot plate, thermometer, measuring spoons, safety goggles and gloves.

What to do:

1. Solubility Test:

a) Fill two beakers with equal amounts of distilled water.

b) Label them as Powder A and Powder B.

c) Add a teaspoon of Powder A to one beaker and a teaspoon of Powder B to the other.

d) Stir each solution until the substances dissolve.

Note how quickly each substance dissolves and whether any residue is left.

2. Conductivity Test:

a) Use a multimeter to measure the electrical conductivity of both solutions.

b) Record the readings for the solutions of Powder A and Powder B.

Note which solution conducts electricity and which does not.

3. Melting Point Test:

a) Place a small amount of Powder A on one side of a hot plate and a small amount of Powder B on the other.

b) Slowly increase the temperature and observe the temperature at which each substance starts to melt.

Note the melting points of both substances.

From your observations, conclude which substance is table salt (ionic) and which is sugar (covalent). Find explanations in Annex 2.3.

Understanding the composition and naming of binary compounds is crucial for identifying the types of chemical bonds and the elements involved. Ionic compounds form through the transfer of electrons between metals and non- metals, leading to the creation of cations and anions. Covalent compounds form through the sharing of electrons between non-metals.

Activity 15

1.

Element - An element is a substance that is made up of only one kind of atom.

Ion - Atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

Molecule - A particle which consists of two or more atoms chemically bonded together.

Compound - A substance made up of two or more different chemical elements combined in a fixed ratio.

2.

H₂O – molecule and compound O₂- molecule NaCl – molecule and compound Fe - element Ca²⁺- ion

Activity 16

Clue 1: This is table salt. The elements in table salt are sodium (Na) and chlorine (Cl).

Clue 2: This is water. The elements in water are hydrogen (H) and oxygen (O).

Clue 3: This is carbon dioxide. The elements in clue 3 are carbon (C) and oxygen (O).

Activity 17

You will observe that calcium loses two electrons while chlorine receives one electron. Two chlorine atoms are therefore needed to take up or accept the two electrons from calcium to balance the reaction. Your diagram may look like this:

Giving CaCl₂.

Ca – 2e- -------> Ca²⁺ (2,8,8,2) (2,8,8) 2Cl + 2e- ---------> 2Cl - (2,8,7) (2,8,8) Ca²⁺+ 2Cl- ---------> CaCl₂

Activity 18

You would observe that there was no reading by the ammeter when the probes were placed in the distilled water. Pure water does not conduct electricity because it does not contain ions, so the electrons do not move through the solution. Thus, pure water is a poor conductor of electricity and is actually an excellent insulator.

There was no reading either when sugar was dissolved in the water. Sugar

solution is also a poor conductor of electricity because sugar molecules are neutral and don’t have a charge. When sugar is dissolved in water, it doesn’t break apart into ions, so the solution only contains neutral sugar and water molecules. These neutral molecules can’t attract to and move to opposite ends of electrodes like ions can, so they can’t conduct electricity.

However, when the salt (NaCl) was added, the ammeter gave some readings.

This is because the salt dissolves into ions, which means that the electrons can move freely through the solution.

Activity 19

Solubility Test - Usually, ionic compounds like NaCl dissolve easily/faster in water, dissociating into ions, while covalent compounds like sugar disperse without dissociation.

Conductivity Test - The solution of the ionic compound (NaCl) conducts electricity because it dissociates into ions. The solution of the covalent compound (sugar) does not conduct electricity because it does not form ions in water.

Melting Point Test - The ionic compound (NaCl) has a higher melting point due to strong ionic bonds. The covalent compound (sugar) has a lower melting point because covalent bonds are generally weaker than ionic bonds.

Conclusion:

• Ionic Compounds: High melting and boiling points, conduct electricity in solution, generally soluble in water, composed of positive and negative ions.

• Covalent Compounds: Low melting and boiling points, do not conduct electricity in solution, may or may not be soluble in water, composed of molecules with shared electrons.

Hello, learner. Please follow the steps below to learn how to write the chemical formula for a compound!

1. Identify the two elements present in the compound.

2. Write the chemical symbols of the two elements that combine to make up the binary compound. In an ionic compound, the atom that forms a positive ion (cation) is written first followed by the negative ion (anion).

3. Determine the valency of each of the atoms. Valency is the combining power of an element. It refers to the number of electrons that an atom loses or gains to form a compound with a different element. Knowing the charge on an ion gives an important clue about its valency. E.g., Mg²⁺has a valency of 2, N+ has a valency of 1, O²⁻has a valency of 2 and Cl- has a valency of 1.

4. Exchange the valencies of the two different elements and write them as subscripts at the right-hand side of the chemical symbol of each atom. In the

example below, the cation of magnesium (Mg²⁺) has a valency of 2 which is exchanged with the valency of the anion of nitrogen (N³⁻) which is 3.

5. Simplify the subscripts by finding the common factor. This step is often skipped if the values are already simplified.

6. Additionally, if the valency is one (1), it is not written.

Another example: Let us consider the compound formed between calcium (Ca) and oxygen (O).

Calcium is a metal and forms cations with a charge of +2. Oxygen is a non-metal and forms anions with a charge of -2.

Based on their charges, it can be inferred that each of these atoms has a valency of 2.

The valences of the two atoms are exchanged as shown in the preceding paragraph.

Because 2 is a common factor to the two subscripts, the subscripts are simplified by dividing each of them by two, giving us the chemical formula of the compound as CaO.

Activity 20:

When naming a binary compound, the first word is always the name of the positive ion (cation). The second word is derived from the name for the negative ion (anion) but ends in the letters ‘ide’. For each of the following compounds A-E, give the correct word that would appear as the second word in its name:

1. KCl

2. CaS

3. AlI3

4. Al2O3

5. Ba3N2

6. NaCl Indicate which of these is a common household substance and give the name of the substance.

Activity 21:

Aim: To write the formula for various compounds including sodium chloride Materials needed: Cuttings of cardboard with names of different elements, written in words and symbols with different charges e.g.

Na 1+ Na 2 - Na 2- Na 3+ Cl 3+ Cl 2 - Mg 2- Mg 2+ Mn 2- I 1+ I - 1- I 2+ I 2- O 2- O 2+ - O 2- O 1- Method:

1. Create your cards (as listed above).

2. Pick a pair of cards with the correct symbols and charge for the following named elements: sodium and chlorine, manganese and chlorine, potassium and iodine, sodium and iodine.

3. Put the pair side by side.

4. Draw a cross (X) as shown in the examples above for the pair of elements you have selected.

5. Write their charges and exchange their numbers as valencies.

6. Write the formula of the combination of the pair of elements.

7. Simplify the result if required.

8. Name the resultant compound formed.

9. Have a go with a few more pairs of elements!

Activity 22

Create a flowchart for writing the formula of the binary compound KCl Aim: To draw a flowchart to write the formula of a binary compound Materials needed: Potassium metal, boiling tube containing chlorine gas, fume cupboard.

Method: (note: this demonstration should only be performed by your teacher;

chlorine gas is poisonous):

1. Observe your teacher drop the piece of the potassium metal in the tube of chlorine gas.

2. Observe what happens in the boiling tube.

3. Draw a flowchart or write a step-by-step method which could be used by another student to find the chemical formula of the compound produced.

Include an explanation as to how the compound should be named.

Activity 20

A) KCl - Chloride B) CaS - Sulfide C) AlI3 - Iodide D) Al2O3 - Oxide E) Ba3N2 – Nitride F) NaCl – Chloride (sodium chloride – table salt)

Activity 22

Annex 2.4 – Further information

• Element: An element is a substance that cannot be broken down into any other substance. Every element is made up of its own type of atom.

This is why the chemical elements are all very different from each other.

Examples iron, Sulphur, gold, chlorine.

• Atom: The smallest part of a substance that can be broken down chemically into fundamental particles. Each atom has a nucleus (centre) made up of protons (positive particles) and neutrons (particles with no charge). Electrons (negative particles) move around the nucleus.

• Electron: is a negatively charged subatomic particle that can be either bound to an atom or free (not bound). An electron that is bound to an atom is one of the three primary types of particles within the atom - the other two are protons and neutrons.

• Valence: A whole number that represents the ability of an atom or a group of atoms to combine with other atoms or groups of atoms. The valence is determined by the number of electrons that an atom can lose, add, or share.

• Valency: is the number of atoms of a particular element that is combined with one atom of another element to form a molecule. Valency is a measure of the combining power of an atom. The valency of an element is determined by the number of electrons in its outermost shell.

• Ion: any atom or group of atoms that bears one or more positive or negative electrical charges. Positively charged ions are called cations;

negatively charged ions, anions. For example, Na+, Cl-

• Compound: a substance made from two or more different elements that have been chemically joined. Examples of compounds include water (H₂O), which is made from the elements hydrogen and oxygen, and table salt (NaCl), which is made from the elements Sodium and Chlorine.

• Binary Compound: is a chemical substance that is made of two different elements only. An element is the fundamental building block of all chemical compounds. The presence of only two different elements in a compound is what classifies a compound as a binary compound.

• Chemical Formula: A chemical formula identifies each constituent element by its chemical symbol and indicates the proportionate number of atoms of each element.

1. Find out the social uses of the following binary compounds: CO₂; NaCl;

CaCl₂; H₂O; MgO by browsing the internet entering “Social uses of binary compounds” in your search bar.

1. Refer to the following references on Page and read about other forms of naming binary compounds. E.g. IUPAC Naming.

Review Questions 2.1

1. Enumerate three properties each of metals, non-metals and semi-metals.

2. In tabular form, outline four differences between metals and non-metals.

3. Explain why metal objects should be kept dry and clean.

4. Explain how metals are used in the production of cooking utensils and why certain metals are chosen for specific cooking tasks.

5. Discuss the role of non-metals in the manufacturing of electronic devices and semiconductor components.

Research Work

6. Use the internet and other resources to search on the topic ‘how are semi- metals utilized in the production of solar panels and other renewable energy technologies?’ Present your report which should include posters, diagrams and charts about your findings to the class.

Review Questions 2.2

1. For each of the following properties, list as many everyday items as you can think of which rely on them:

o High conductivity o Magnetic properties o Lustre o High melting and boiling points

2. Why is it important for metallic cookware be designed including materials that are good conductors but also materials that are good insulators?

Review Questions 2.3

1. Identify at least four examples of binary compounds in everyday life.

2. Describe how magnesium oxide is formed.

3. Explain the role of electron transfer in the formation of binary ionic compounds.

4. Explain how covalent compounds are different from ionic compounds.

Give precise examples to support your explanation.

Research Work

Evaluate the importance of understanding the differences between ionic and covalent compounds in practical applications, such as in medicine, materials science, and environmental science and present your findings in class.

Review Questions 2.4

1. Two elements X and Y have charges +3 and -2 respectively. Write the molecular formula for the compound formed.

2. Write the formula of a compound made of elements Y and Z whose valences are 2 and 2 respectively.

3. What basic concepts of naming binary compound will you consider if you are working alone? You may work with a friend to share your views on the concepts of naming binary compounds and put your views together and come out with patterns and rules to be used in naming binary compounds.

4. Name the following compounds and indicate the valencies of each component element in the compound:

a) MgCl₂

b) CO₂

c) Na₃N

d) BeO

e) MgH₂

f) KI