CDS Chemistry · Teaching notes
Metals and Non-Metals — CDS Chemistry
Metals and Non-Metals has 22 past-year questions in CDS General Knowledge, from 2018 (II) to 2026 (II), most of them EASY or MODERATE. CDS repeats itself here more than anywhere else in chemistry: why silver turns black has been asked three times, the order Mg > Al > Zn > Fe twice, and sodium under kerosene twice. So the reactivity series is the one list to know cold, since it also predicts which metal gives hydrogen with an acid and which displacement will happen.
Every subtopic, worked example, formula and trap in one printable document — answers shown, ready to share.
Subtopic notes
Properties of Metals, Non-Metals and Metalloids
5 PYQsThe physical properties that mark a metal, the non-metals that break the rules, and the metalloids that sit between.
The Reactivity Series
8 PYQsThe order of metals by reactivity, what it predicts about acids, oxygen and displacement, and why the most reactive metals are stored under oil.
Extraction of Metals and Alloys
4 PYQsWhich ore gives which metal, roasting against calcination, why the most reactive metals need electrolysis, and what common alloys are made of.
Corrosion and Its Prevention
5 PYQsWhat iron, silver and copper turn into when they corrode, and the ways corrosion is stopped, anodising included.
Formula & revision sheet
1 formulas · 8 reference tables · 12 gotchas across all subtopics — the exam-eve cheat-sheet
Formula & revision sheet
1 formulas · 8 reference tables · 12 gotchas across all subtopics — the exam-eve cheat-sheet
Reference tables (2)
Physical properties of metals4 rows
| Property | Meaning | Example |
|---|---|---|
| Malleable and ductile | Beaten into sheets; drawn into wires | Gold, the best at bothQ |
| Sonorous | Rings when struck | School bellsQ |
| Lustrous | Shiny surface | Polished silver |
| Good conductor | Carries heat and electricity | Silver best, then copperQ CDS 2022 (II): silver and copper are the pair of very good heat conductors; lead and mercury are poor. |
Non-metals that break the rules, and metalloids6 rows
| Element | Kind | Notable property |
|---|---|---|
| Iodine | Non-metal | Lustrous (shiny)Q CDS 2021 (I): iodine is the non-metal that is lustrous. Silicon and germanium are metalloids, not non-metals. |
| Graphite | Non-metal (carbon) | Conducts electricity |
| Diamond | Non-metal (carbon) | Hardest natural substance |
| Germanium | Metalloid | SemiconductorQ |
| Silicon | Metalloid | Semiconductor |
| Boron, arsenic, antimony, tellurium | Metalloids | Properties of both metals and non-metals |
Watch out for (2)
- Mercury is neither malleable nor ductile→ Physical properties of metals
- Silicon and germanium are metalloids→ Non-metals that break the rules, and metalloids
Reference tables (2)
The reactivity series and reactions with acids6 rows
| Metal | Reaction with dilute HCl | Reaction with oxygen |
|---|---|---|
| K, Na, Ca | Violent | Burn readily |
| Mg | Fast; gives H₂ | Burns with a white flameQ CDS 2018 (II): magnesium with hydrochloric acid is the pair that gives hydrogen. |
| Al, Zn, Fe | Slower in that order; gives H₂ | Form oxides |
| Pb | Very slow | Forms an oxide |
| Cu | No reaction (below H) | Forms a black oxide when heated |
| Ag, Au | No reaction | Do not form an oxideQ CDS 2020 (II): silver is the metal that does not form an oxide with oxygen. |
Watch out for (4)
- Nitric acid rarely gives hydrogen→ The reactivity series and reactions with acids
- Zinc sits above iron→ The reactivity series and reactions with acids
- Only the higher metal displaces→ Displacement: a more reactive metal pushes out a less reactive one
- Sodium is under kerosene because of moisture, not evaporation→ Why reactive metals are stored under oil
Reference tables (2)
Ores and how metals are extracted6 rows
| Metal | Main ore | Extracted by |
|---|---|---|
| Aluminium | Bauxite (Al₂O₃·2H₂O) | Electrolysis of aluminaQ |
| Sodium | Rock salt (NaCl) | Electrolysis of fused NaClQ CDS 2025 (II): sodium is the metal won by electrolysis of its molten compound. |
| Iron | Haematite (Fe₂O₃) | Reduction with coke in a blast furnace |
| Zinc | Zinc blende (ZnS) | Roasting, then reduction with carbon |
| Mercury | Cinnabar (HgS) | Roasting |
| Copper | Copper pyrites (CuFeS₂) | Roasting and smelting |
Common alloys and what they are made of6 rows
| Alloy | Made of | Used for |
|---|---|---|
| Solder | Lead and tin | Joining wires (low melting point)Q |
| Brass | Copper and zinc | Fittings, instruments |
| Bronze | Copper and tin | Statues, medals |
| Stainless steel | Iron, chromium, nickel | Utensils; does not rust |
| Duralumin | Aluminium, copper, magnesium, manganese | Aircraft bodies |
| Amalgam | Mercury with another metal | Dental fillings |
Watch out for (3)
- Roasting is for sulphides, calcination for carbonates→ Ores and how metals are extracted
- Electrolysis is for the most reactive metals→ Ores and how metals are extracted
- Brass has zinc, bronze has tin→ Common alloys and what they are made of
Reference tables (2)
Preventing corrosion, and anodising4 rows
| Method | How it protects |
|---|---|
| Painting, oiling | Keeps air and moisture away |
| Galvanising | Zinc coat corrodes first, protecting iron |
| Electroplating, tinning | Coat of a less reactive metal |
| Anodising | Aluminium as the anode; O₂ at the anode thickens the oxide filmQ CDS 2023 (I), HARD: 'oxygen gas is evolved at the cathode' was the false statement. |
Watch out for (3)
- Silver does not form an oxide→ What each metal forms when it corrodes
- In anodising, oxygen forms at the anode→ Preventing corrosion, and anodising
- Galvanising uses zinc, not tin→ Preventing corrosion, and anodising
PYQ weightage by concept
9 concepts · 22 PYQs — where the marks actually sit, so you know what to drill first
PYQ weightage by concept
9 concepts · 22 PYQs — where the marks actually sit, so you know what to drill first
| Concept | PYQs | Share |
|---|---|---|
| Physical properties of metals | 3 | 14% |
| Non-metals that break the rules, and metalloids | 2 | 9% |
| Concept | PYQs | Share |
|---|---|---|
| The reactivity series and reactions with acids | 4 | 18% |
| Why reactive metals are stored under oil | 3 | 14% |
| Displacement: a more reactive metal pushes out a less reactive one | 1 | 5% |
| Concept | PYQs | Share |
|---|---|---|
| Ores and how metals are extracted | 3 | 14% |
| Common alloys and what they are made of | 1 | 5% |
| Concept | PYQs | Share |
|---|---|---|
| What each metal forms when it corrodes | 4 | 18% |
| Preventing corrosion, and anodising | 1 | 5% |
Test yourself on Metals and Non-Metals
10 past CDS questions from this chapter, timed at 10 minutes and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.