Periodicity

In this section, you will learn about a fascinating group of metals known as transition elements. These metals are distinct from the main group elements because of their unique properties. For instance, they can display different oxidation states, meaning they have more than one charge. You will also discover that transition elements often form colourful compounds, can act as catalysts in chemical reactions, and readily form complex compounds with other molecules.

By the end of this section, you will have the skills to find transition elements on the Periodic Table, explain their special properties through hands-on experiments, and understand how complex compounds are formed and named. Additionally, you will compare transition elements with main group metals and appreciate their numerous applications in daily life, including their roles in construction, electronics, medicine, and environmental protection.

KEY IDEAS

· Transition elements: a special group of metals in the middle of the periodic table (d-block) with unique properties.

· Variable oxidations state: the ability to show more than one charge · Complex compound: a compound where a transition metal ion bonds with other molecules/ions called ligands (e.g., [Cu(NH₃)₄]²+).

Transition Elements

What are Transition Elements?

Transition elements are elements with a partially filled d sub-shell or the capacity to produce cations with an incomplete d sub-shell. Transition elements are special metals found in the middle of the periodic table (Groups 3–12). They have a partly filled d-orbital. Because of this, they can form different ions (charges) and show many unique properties.

Note

Zinc, cadmium, and mercury usually have their d-orbitals filled. They do not always behave like typical transition metals, but we still study them as part of this group.

The general way we write electron configurations is: [noble gas] d¹–¹⁰ns¹–².

Some elements (like chromium and copper) are exceptions because it is more stable for them to have half-filled or filled d-orbitals.

Properties of Transition Elements

Physical Properties

1. Good conductors of heat and electricity.

2. High melting and boiling points (except mercury).

3. Hard and strong metals (used in construction).

4. High density compared to main group metals.

5. Malleable and ductile (can be shaped and stretched).

Characteristic Properties of Transition Elements

1. Variable Oxidation States

Transition metals can lose different numbers of electrons, forming ions with different charges. For example, Iron can exist as Fe²+ (iron II) or Fe³+ (iron III).

Application: This allows them to take part in many redox reactions.

For example, manganese dioxide (MnO₂) with Mn⁴⁺is used in dry cells (batteries).

2. Coloured Compounds

Transition metals often form salts and solutions that have bright colours due to d–d electron transitions. For example, Copper (II) sulphate is blue, potassium dichromate is orange, nickel compounds are green.

Application: Used as colouring agents in paints, inks, ceramics, stained glass, and fireworks.

3. Catalytic Properties

Transition metals and their compounds speed up reactions by providing an alternative pathway with lower activation energy. They are not used up in the process. For instance, Iron is a catalyst in the Haber process (making ammonia).

Application: Used as industrial catalysts e.g.,

a. Iron (Fe) for ammonia production.

b. Vanadium(V) oxide (V₂O₅) in manufacturing of sulfuric acid (Contact process).

c. Platinum (Pt) as catalytic converters in car exhaust systems.

4. Complex Formation

Transition metals form complex ions by bonding with other ions or molecules (ligands). Example: [Cu(NH₃)₄]²+ is where copper forms a complex with ammonia.

Application: Complexes are used in medicine (cisplatin, a platinum complex, is used to treat cancer) and analytical chemistry (detecting and identifying ions).

5. Magnetism Some transition elements (iron, cobalt, nickel) have unpaired d-electrons that make them magnetic.

Application: Used to make magnets for electric motors, transformers, loudspeakers, and data storage devices.

6. High Melting and Boiling Points

Transition metals have strong metallic bonds due to delocalised d-electrons, giving them high melting and boiling points.

Application: Used in construction of buildings, bridges, and tools where strong and heat-resistant materials are needed (e.g., tungsten filaments in bulbs).

7. Good Conductors of Heat and Electricity

The presence of delocalized electrons allows easy flow of charge and heat.

Application: Copper wires for electrical wiring, silver in electronics, platinum in electrodes.

Experiments to Show Catalytic Behaviour

General Safety (read before you start) Wear goggles and gloves. Handle 3% H₂O₂with care; avoid eyes/skin.

Do not inhale powders (e.g., MnO₂). Clean spills with plenty of water.

Dispose of solutions per school policy; do not pour heavy-metal salts down the sink.

Decomposition of Hydrogen Peroxide with Manganese

(IV) Oxide (MnO₂) Aim: Show that a transition element catalyst speeds decomposition of H₂O₂and is not consumed.

Materials

1. 3% H₂O₂(30–50 ml)

2. A pinch of MnO₂

3. 100 ml beaker

4. Gas collection (syringe or inverted cylinder)

5. Stopwatch

6. Filter paper (to recover MnO₂) Procedure

1. Set up to collect oxygen gas from the beaker.

2. Add H₂O₂to the beaker and start the timer the moment you add a pinch of MnO₂.

3. Record the O₂volume every 10–20 s for 2–3 minutes.

4. Repeat a control run with the same H₂O₂but without MnO₂.

Table 1A: Catalysed run (MnO₂present) Time / s O₂volume / mL

Table 1B: Control run (no catalyst) Time / s O₂volume / mL Record/Observe Compare bubble rate catalysed vs control.

Filter, wash, dry MnO₂and note that mass/appearance remains (not consumed).

Confirm through a suitable gas test that the gas collected is in fact oxygen.

Calculations (show working)

1. Plot O₂volume (mL) vs time (s) for both runs on the same axes.

2. From initial slope, compare relative rates.

3. Explain in terms of activation energy and surface sites.

4. Write the balanced chemical reaction for this experiment (remember to include the state symbols).

Iodide-Catalysed Decomposition of Hydrogen Peroxide

(KI) Aim: Show that a dissolved iodide catalyst speeds up O₂release and is regenerated.

Materials

1. 3% H₂O₂(20–30 ml)

2. KI solution (0.1 M) or a few crystals

3. Dish soap (1 drop) + food colouring (optional)

4. Small beaker/cylinder

5. Ruler (to measure foam height)

6. Stopwatch Procedure

1. Place H₂O₂and one drop of soap in the beaker. Start the timer when KI is added.

2. Measure foam height every 10–15 s until it stops rising.

3. Repeat a control without KI.

Table 2A: With KI (catalyst present) Time / s Foam height / cm

Table 2B: Control (no KI)

Time / s Foam height / cm Record/Observe

Note immediate vs delayed foam formation.

Record maximum foam height and time to reach it.

Calculations (show working)

1. Plot foam height vs time for both runs.

2. Relate observations to the iodide catalytic cycle (I– → I₂→ I–).

Check-Your-Understanding

1. Why does adding more KI (small increase) usually shorten the time to peak height?

2. State how the catalyst is regenerated in this reaction.

Transition-Metal Catalysis: Fe³+/Fe²+ in the Persulphate–

Iodide Reaction (‘Iodine Clock’ variant) Aim: Show a transition metal ion catalyst speeds a reaction via an electron-shuttle and is regenerated.

Materials

1. 0.02 M K₂S₂O₈(persulfate)

2. 0.02 M KI (iodide)

3. Starch indicator

4. M FeCl₃(few drops as catalyst)

5. Beakers, measuring cylinders, stopwatch Procedure

1. Prepare two identical mixtures of persulphate + iodide + starch.

2. Add a few drops of FeCl₃to only one mixture (catalysed). Start timing both.

3. Record time to blue colour (starch–iodine complex) for each.

4. Optional: vary Fe³⁺volume and repeat.

Table 3A: Time to blue (with and without Fe^(³+)) Trial Fe³+? (Y/N) Fe³+ volume / drops Time to blue / s

Table 3B: Extension — Effect of Fe³+ amount Fe³+ drops Time to blue / s Record/Observe Compare times catalysed vs uncatalysed.

Describe the colour change clearly.

Calculations (show working) Explain Fe cycling between Fe²+ and Fe³+ and how that speeds the net reaction.

Check-Your-Understanding

1. What evidence shows Fe³+ is a catalyst, not a reactant?

2. Predict what happens if Fe³+ is doubled.

Activity 5.1 Understanding Transition Elements

1. Form a group with 4-5 classmates.

2. Use the periodic table to identify the first-row transition elements (Sc to Zn). Point them out together.

3. Write your own simple definition of transition elements.

4. Identify the characteristic properties of transition elements and describe each property with the help of textbooks.

5. Discuss and note key ideas as a whole class

a. Where transition elements are on the periodic table.

b. Their electronic configuration and d-orbitals.

c. How properties are linked to electron structure.

d. Real-life uses in Ghana (e.g., mining, manufacturing, catalysts).

Copper Complex Formation Experiment

Aim: To observe how copper (II) ions form a deep-blue complex with ammonia and understand applications of complexes.

Materials

1. Copper (II) sulphate solution (dilute)

2. Ammonia solution (dilute)

3. Sodium hydroxide solution (dilute)

4. 3 test tubes + rack

5. Droppers/pipettes

6. Wooden splint + matches

7. White paper (to see colours clearly)

8. Beaker for waste, water for rinsing Safety

1. Wear goggles.

2. Do not sniff ammonia; work in a ventilated space.

3. Wash hands after the experiment.

4. Teacher handles any spills.

Procedure

1. Put 2–3 ml of CuSO₄in Test Tube 1. Note the pale blue colour.

2. Add ammonia drop by drop. At first, a light blue solid may appear.

3. Add more ammonia (excess) – the solid dissolves to give a deep royal blue

solution.

4. In Test Tube 2, put 2–3 ml CuSO₄and add NaOH solution drop by drop. A light blue solid forms.

5. Add ammonia to this tube – the solid dissolves and turns deep blue.

6. For the mystery test, add ammonia to two clear solutions (A and B). The one that turns deep blue contains copper ions.

Results Table

Tube What we added What we saw What it means 1 CuSO₄+ excess NH₃ Deep royal blue

solution

Copper–ammonia complex formed 2 CuSO₄+ NaOH Light blue solid (Cu(OH)₂) Hydroxide precipitate 2 → then NH₃ Added ammonia to the solid Solid dissolves → deep blue Complex re- dissolves the solid Mystery + NH₃ Deep blue or no change Cu²+ present or absent

Note

· Copper ions bond with ammonia to form a deep-blue complex.

· Sodium hydroxide only gives a pale blue solid (Cu(OH)₂).

· Complexes absorb light differently, giving colours.

· Complexes are important in industry, mining, medicine, and testing for ions.

Real-life Applications

1. Identification test: The deep-blue colour helps confirm copper in a sample (school labs, water testing).

2. Cleaning & extraction: Ammonia and other ligands help dissolve or separate metals in mining and recycling.

3. Medicine & analysis: Metal complexes are used for drug delivery and detecting ions (analytical chemistry).

4. Textiles & materials: Some copper complexes colour fabrics, glass, and ceramics.

Shapes of Common Complex Compounds

a. Linear Complexes (2 ligands opposite each other) Shape: Straight line.

Hyhridisation of central atom: sp Examples: [Ag (NH₃)₂] + (Tollen’s reagent), [CuCl₂] −

b. Square Planar Complexes (4 ligands in one flat plane) Shape: Flat square arrangement.

Hyhridisation of central atom: dsp²Examples: [Ni (CN)₄]²⁻, [Pt (NH₃)₂Cl₂] (cisplatin – used in cancer treatment)

c. Tetrahedral Complexes (4 ligands around the metal, not flat) Shape: Like a 3D pyramid with a triangular base.

Hyhridisation of central atom: sp³Examples: [CuCl₄]²⁻, [ZnCl₄]²⁻d. Octahedral Complexes (6 ligands around the metal) Shape: Looks like two square pyramids joined base to base.

Hyhridisation of central atom: sp³d²Examples: [Cu (H₂O)₆]²⁺, [Fe (CN)₆]³⁻, [Co (NH₃)₆]³⁺Note The number of ligands (coordination number) determines the shape. Transition metals can form different shapes depending on the ligands.

Diagrams of octahedral, tetrahedral, square planar, linear shapes Naming Complex Compounds Scientists use special naming rules (IUPAC rules) to describe them clearly.

The name tells us:

1. The ligands (what is attached to the metal).

2. The number of ligands.

3. The metal in the centre.

4. The oxidation state (charge) of the metal.

This system makes sure every chemist around the world understands the same compound in the same way.

Example

[Cu (NH₃)₄]SO₄is called tetraamminecopper (II) tetraoxosulphate (VI).

“Tetraammine” = 4 ammonia ligands.

“Copper (II)” = copper with a +2 charge.

“Sulphate” = the outside ion.

Step-by-Step Guide

1. Name the Ligands (in alphabetical order) Negative ligands: change ending to –o (Cl– → chloro, CN– → cyano) Neutral ligands: keep normal name (NH₃→ ammine, H₂O → aqua)

2. Use Prefixes for Number of Ligands

1 = mono-, 2 = di-, 3 = tri-, 4 = tetra-, 5 = penta-, 6 = hexa-

3. Name the Central Metal

Neutral/positive complex → normal metal name (e.g., copper, iron) Negative complex → add –ate (Fe → ferrate, Cu → cuprate)

4. Add the Metal’s Oxidation State

Shown in Roman numerals in brackets (e.g., Copper (II) = Cu²+)

5. Add Any Outside Ions

If part of a salt, add the outside ion last (e.g., SO₄²– = sulfate, Cl– = chloride) Examples

1. [Cu (NH₃) ₄]SO₄ 4 ammonia ligands = tetraammine Metal = copper Oxidation state = (II) Outside ion = sulphate Name: tetraamminecopper(II) tetraoxsulphate

2. [Fe (CN)₆] ³– 6 CN– ligands = hexacyano Negative complex → ferrate Oxidation state = (III) Name: hexacyanoferrate (III) ion

3. [CoCl₄] ²– 4 Cl– ligands = tetrachloro Negative complex → cobaltate Oxidation state = (II) Name: tetrachlorocobaltate (II) ion Practice Questions Name the following complexes

1. [Cr(H₂O) ₆] ³+

2. [Zn (NH₃) ₄] ²+

3. [Pt (NH₃) ₂Cl₂]

4. [Fe(H₂O) ₆] ²+

5. [Ni (CN)₄] ²– Tip: Always follow the order: [Ligands → Metal + Oxidation State → Outside Ion]

Activity 5.2 Solubilising Insoluble Compounds

Aim: To explore how some insoluble compounds dissolve when ligands form complexes.

Work in small groups of learners. Each group will carry out the steps and record observations.

Steps

1. Prepare test solutions: Copper (II) sulphate (CuSO₄), Silver nitrate (AgNO₃), Zinc sulphate (ZnSO₄).

2. Form insoluble precipitates by adding sodium hydroxide (NaOH) or sodium chloride (NaCl).

3. Add ligand solutions like ammonia (NH₃) or excess NaOH drop by drop to the precipitate

4. Observe colour changes and note if precipitates dissolve.

5. Record results in a table.

6. Write balanced equations for

a. Precipitate formation.

b. Complex ion formation.

7. Discuss applications of complex formation in real life.

8. Explain why complex formation is important in

a. Water treatment (removing unwanted ions).

b. Medicine (metal complexes in drugs).

c. Mining and extraction (dissolving ores).

d. Analytical chemistry (detecting ions).

Observation Table

Compound + Reagent Precipitate Formed Effect of Excess Ligand Final Colour/ Observation CuSO₄+ NaOH Blue Cu (OH)₂ solid Dissolves in excess NH₃ Deep blue

solution

AgNO₃+ NaCl White AgCl solid Dissolves in excess NH₃ Colourless

solution

ZnSO₄+ NaOH White Zn (OH)₂

solid Dissolves in excess NaOH Colourless

solution

Results Table

Compound + Reagent Precipitate Formed Effect of Excess Ligand Final Colour/ Observation _________ _________ _________ _________ _________ _________ _________ _________ _________ _________ _________ _________ Balanced Equations

1. __________________________________________

2. __________________________________________

3. __________________________________________

Activity 5.3 Modelling Complex Geometries

Build a 3D model → Draw a 2D picture → Name the complex Aim: Work in groups to:

1. build a 3D model of a metal complex

2. draw the 2D representation

3. correctly name the complex (IUPAC) Group Roles Reader – reads the task card Builder – leads the model construction Angle Checker – checks shape & angles Artist/Recorder – draws 2D + writes name Presenter – explains to class Materials Modelling kits or: beads/buttons (metal), small beads (ligands) Pipe cleaners/straws/toothpicks (bonds), plasticine (joints) Rulers, markers, A4 paper Shape cards:

1. Tetrahedral

2. Square planar

3. Octahedral

Step 1: Get your shape card Tetrahedral: 4 bonds, angles ≈ 109.5° Square planar: 4 bonds in a flat square, angles 90°/180° Octahedral: 6 bonds, angles 90°/180° Pick one example to build:

1. Tetrahedral: [ZnCl₄] ²–

2. Square planar: [Pt (NH₃) ₂Cl₂]

3. Octahedral: [Fe(H₂O) ₆] ²+, [Co (NH₃) ₆]³+

Step 2 : Build your 3D model Put the metal bead in the middle Add the correct number of ligand beads around it Use straws/pipe cleaners as bonds Angle Checker: confirm flat (square planar), 109.5° (tetrahedral), 6 at right angles (octahedral)

Step 3: Draw the 2D picture Square planar: draw a square with M in the centre; ligands at corners Tetrahedral/Octahedral (use cues):

Solid line = in the plane Wedge ▲= coming out of the page Dash ▬ ▬ = going behind the page

Step 4: Name your complex (IUPAC) Order ligands alphabetically (ignore di-/tri- when alphabetising) Add number prefixes: di-, tri-, tetra-, penta-, hexa- Write the metal name with oxidation state in Roman numerals if known Examples

1. [Fe(H₂O) ₆] ²+ → hexaaquairon (II) ion

2. [Pt (NH₃) ₂Cl₂] → diamine dichloro platinum (II) ion

3. [ZnCl₄] ²– → tetrachloro zincate (II) ion (anionic complexes often end in “-ate”)

Step 5: Present to the class Show your 3D model and 2D drawing Say the name and why the shape fits (number of ligands + angles)

Step 6: Connect to properties CN = 4 can be tetrahedral or square planar (affects colour & magnetism) Octahedral is common for d-block ions in water (e.g., [Fe(H₂O) ₆] ²+) Real life: catalysts (Pt), pigments/colours (Cu/Ni), medicine (cis-platin) Quick Naming Helper Common ligands Prefixes Metals ammine (NH₃) di- (2) iron (II/III) aqua (H₂O) tri- (3) copper(I/II) chloro (Cl–) tetra- (4) zinc (II) cyano (CN–) penta- (5) nickel (II) hexa- (6) platinum (II) Success Check (tick √) Correct geometry (tetrahedral / square planar / octahedral).

Clear 2D drawing (use wedge/dash where needed).

Ligands in alphabetical order + correct prefixes.

Correct metal name with oxidation state.

Presenter explains shape: # ligands + angles.

Similarities Between Transition Metals and Main

Group Metals

1. Metallic Nature – Both are metals, so they are shiny (lustrous).

2. Conductivity – Both can conduct heat and electricity.

3. Malleability and Ductility – Both can be hammered into sheets (malleable) and stretched into wires (ductile).

4. High Melting and Boiling Points – Most of them are strong and have high melting/boiling points.

5. Form Positive Ions – Both lose electrons easily to form cations.

6. Form Metallic Bonds – In both, atoms are held together by metallic bonding (delocalised electrons).

7. Useful in Everyday Life – Both are used in construction, tools, coins, and machines.

Differences Between Transition Metals and Main

Group Metals

Table 5.1: Differences between transition metals and group metals Feature Transition Metals Main Group Metals Position on Periodic Table Found in the middle (Groups 3–12, d-block) Found on the left and right (s- and p-block) Oxidation States Show variable charges (e.g., Fe²+, Fe³+) Usually have fixed charges (e.g., Na+, Mg²+) Compound Colour Form coloured compounds/ solutions (e.g., blue Cu²+) Mostly form colourless compounds Feature Transition Metals Main Group Metals Catalytic

Activity

Many acts as catalysts (e.g., Fe in Haber process) Rarely act as catalysts Complex Formation Readily form complex ions with ligands Rarely form complexes Magnetic Properties Some (Fe, Co, Ni) are magnetic Usually not magnetic Strength & Hardness Generally hard and strong Many are softer and lighter (e.g., Na, K) Uses of Transition Metals in Everyday Life

1. Building & Tools

a. Iron/steel (Fe): beams for buildings, bridges, nails, cutlery.

b. Chromium (Cr) + nickel (Ni) in stainless steel: sinks, spoons, roof fasteners (resist rust).

c. Manganese (Mn): makes steel tougher.

2. Electricity & Electronics

a. Copper (Cu): wires, phone chargers, motors (great conductor).

b. Gold (Au) / Silver (Ag): tiny connectors that don’t tarnish easily.

3. Magnets & Motors Iron, cobalt, nickel (Fe, Co, Ni): fridge magnets, speakers, electric motors, generators.

4. Cleans Air in Cars

Platinum, palladium, rhodium (Pt, Pd, Rh) in catalytic converters: change harmful gases into less harmful ones.

5. Batteries & Energy Nickel, cobalt, manganese (Ni, Co, Mn): parts of many rechargeable batteries.

6. Health & Medicine

a. Iron (Fe) in haemoglobin helps blood carry oxygen.

b. Cobalt (Co) is part of vitamin B₁₂.

c. Platinum (Pt) medicines (like cis-platin) help treat some cancers (teacher

note).

7. Colours in Glass & Ceramics

a. Cobalt → deep blue glass/tiles.

b. Chromium → green glass/glazes.

c. Iron → brown/amber bottles.

8. Coins & Jewellery

a. Copper & nickel in many coins.

b. Gold & silver for jewellery.

9. Stopping Rust

Zinc (Zn) coating (galvanised steel) protects fences, roofs, and water tanks.

10. Heat & Cutting Tungsten (W), molybdenum (Mo): very hard, used in drill bits, high- temperature parts.

Activity 5.4 Exploring Transition & Main Group Metals

Step 1

1. Open an interactive periodic table app/website/periodic table chart.

2. Highlight: Transition metals → middle block (Groups 3–12) and Main group metals → left and right side.

3. Underline the metals you see in daily life (coins, wires, pots, jewellery) on the periodic table.

4. Sorts the underlined metals into

a. Transition metals (iron, copper, gold, silver, nickel).

b. Main group metals (sodium, magnesium, aluminium).

5. Work in groups and fill in your comparison chart.

a. Hardness – Compare which are harder: transition metals or main group metals.

b. Reactivity – Watch a video/demo of metals with water or dilute acids. Record which type reacts faster.

c. Charges (Oxidation States) – Research examples of metals with variable charges (e.g., Fe²+, Fe³+) and metals with only one charge (e.g., Na+).

d. Complex Ion Formation – Watch a demo/video of copper with ammonia (deep blue solution). Note which type forms complexes more easily.

e. Coloured Compounds – Observe salts dissolved in water (CuSO₄= blue, Ni²+ = green, Fe³+ = yellow brown). Record colours.

f. Catalysts – Research or watch a video of MnO₂breaking down H₂O₂. Record which metals are used as catalysts.

Comparison Chart: Transition vs Main Group Metals Property Transition Metals (Examples & Observations) Main Group Metals (Examples & Observations) Conclusion (Which type shows this property more?)

Hardness Reactivity (with

water/acid) Charges (Oxidation States) Complex Ion Formation Coloured Compounds Catalysts

6. With your group, create a poster showing uses in:

a. Construction (iron, steel).

b. Technology (copper, silver, gold in electronics).

c. Medicine (cobalt in vitamin B₁₂, platinum drugs).

d. Transportation (steel for cars, trains, ships).

e. Household items (coins, jewellery, cookware).

7. Share your work with the class.

1. a. State two physical properties of transition elements.

b. State two chemical properties of transition elements.

c. Give one reason why transition metals are often used in construction.

2. a. Describe briefly why compounds of transition metals are often coloured.

b. Explain why many transition elements show variable oxidation states while main group metals do not.

c. Give two examples of transition elements used as catalysts and the processes in which they are applied.

3. You are provided with CuSO₄solution, ammonia solution, MnO₂, and H₂O₂.

a. Design an experiment to show that:

i. Transition metal ions can form coloured solutions.

ii. Transition metals or their compounds act as catalysts.

b. Write down the expected observations and chemical equations for the reactions in (a.) above

4. Transition metals play important roles in science and society.

a. Discuss how electronic configuration is linked to:

i. Variable oxidation states.

ii. Formation of coloured compounds.

b. Compare the properties of transition metals with main group metals under:

· Oxidation states · Compound colour · Catalytic properties

c. Explain with examples three ways transition metals are applied in everyday life in Ghana.

5. a. State two similarities between transition metals and main group metals.

b. State two differences between transition metals and main group metals.

c. Give two everyday uses of transition metals.

6. a. Using examples, explain why transition metals often form coloured compounds while main group metals do not.

b. Why are transition metals generally less reactive with water and acids than main group metals?

c. Outline three specific everyday uses of transition metals in construction, technology, and medicine.

7. a. Complete the table with suitable entries.

b. Explain how these properties make transition metals more useful in industry than main group metals.

c. Suggest why aluminium, a main group metal, is still widely used despite these differences.

8. a. Compare transition metals and main group metals under oxidation states, compound colours, catalytic activity, and everyday applications.

b. Discuss the economic importance of transition metals in Ghana.

c. If you were to design a new industrial catalyst, explain why you would choose a transition metal and not a main group metal.