NDA Chemistry · Free notes
Metals and Non-Metals — NDA Chemistry
Metals and Non-Metals is a compact recall chapter — about 18 PYQs across 2017–2026, almost every one a 'which is correct' or 'which is NOT' about reactivity, an ore, corrosion, or an alloy. There is no derivation to do; the marks go to whoever has the reactivity series and the ore/alloy tables memorised. The chapter teaches in four movements, building from general properties up to applications: (1) Reactivity series and reactions with water — the order of metals from most to least reactive, which metals float, which react with cold water versus steam, and the alkali-metal melting-point trend; (2) Extraction of metals and ores — the common ores and the reduction method each metal needs (carbon reduction, electrolysis, or none for native metals); (3) Corrosion and its prevention — why iron rusts, why copper turns green, and how galvanization and sacrificial protection work; (4) Alloys and their composition — what brass, bronze, steel, amalgam, stainless steel and NaK are made of. Most concepts are reference tables: learn the table, win the marks.
The handout has every subtopic, worked example, formula and trap with answers shown. The formula sheet is the chapter’s formulas and traps alone, on one page.
Subtopic notes
Reactivity Series and Reactions with Water
7 PYQsMetals ranked from most reactive (potassium) to least reactive (gold), and how each one behaves toward cold water, hot water and steam.
Extraction of Metals and Ores
2 PYQsThe naturally occurring ores of common metals and the reduction method each metal needs — carbon reduction, electrolysis, or none for native metals.
Corrosion and Its Prevention
5 PYQsWhy metals are eaten away by air and moisture — iron rusting, copper turning green — and how galvanization and sacrificial protection stop it.
Alloys and Their Composition
4 PYQsAlloys are solid mixtures of a metal with one or more other elements — brass, bronze, steel, amalgam — engineered to beat the pure metal on strength, hardness or corrosion resistance.
Formula & revision sheet
0 formulas · 9 reference tables · 11 gotchas across all subtopics — the exam-eve cheat-sheet
Formula & revision sheet
0 formulas · 9 reference tables · 11 gotchas across all subtopics — the exam-eve cheat-sheet
Reference tables (3)
Metals versus non-metals — the property contrast5 rows
| Property | Metals | Non-metals |
|---|---|---|
| Electron behaviour | Lose electrons (electropositive) | Gain/share electrons (electronegative) |
| Appearance | Lustrous (shiny) | Dull (except graphite, iodine) |
| Malleability | Malleable and ductile | Brittle when solid |
| Conductivity | Good conductors | Poor conductors (except graphite) |
| Nature of oxide | Basic | Acidic Metal oxide + water → base; non-metal oxide + water → acid. This is a common 'which statement is correct' test. |
The reactivity series — order of metals3 rows
| Reactivity | Metals (in order) |
|---|---|
| Most reactive | Potassium (K), Sodium (Na), Calcium (Ca) |
| Moderately reactive | Magnesium (Mg), Aluminium (Al), Zinc (Zn), Iron (Fe) |
| Least reactive | Copper (Cu), Mercury (Hg), Silver (Ag), Gold (Au) |
Reactions with water and alkali-metal trends5 rows
| Metal | Reacts with water? | Note |
|---|---|---|
| Potassium / Sodium | Yes, with cold water | Float and react vigorously (less dense than water) Both K and Na float on water; potassium reacts even more vigorously than sodium. |
| Calcium | Yes, with cold water | Reacts steadily, releasing H₂ |
| Magnesium | No (cold); yes with steam | Does NOT react with cold water |
| Iron | No (cold); slow with steam | Does NOT liberate H₂ from cold water |
| Copper | No | Below hydrogen — does not react with water |
Watch out for (4)
- Oxide nature is reversed for non-metals→ Metals versus non-metals — the property contrast
- Iron beats copper, copper beats silver→ The reactivity series — order of metals
- Magnesium and iron do NOT react with cold water→ Reactions with water and alkali-metal trends
- Melting point falls DOWN the alkali group→ Reactions with water and alkali-metal trends
Reference tables (2)
Common ores and their metals6 rows
| Ore | Formula | Metal |
|---|---|---|
| Cinnabar | HgS | Mercury Cinnabar is the ore the bank tests most — it gives mercury. |
| Bauxite | Al₂O₃·2H₂O | Aluminium |
| Haematite | Fe₂O₃ | Iron |
| Zinc blende | ZnS | Zinc |
| Copper pyrites | CuFeS₂ | Copper |
| Galena | PbS | Lead |
Extraction method versus reactivity3 rows
| Reactivity band | Extraction method | Example |
|---|---|---|
| Most reactive (K, Na, Ca, Mg, Al) | Electrolysis of molten ore | Aluminium by electrolysis Carbon CANNOT reduce these — they bind oxygen too strongly. Aluminium is the classic 'needs electrolysis' answer. |
| Moderate (Zn, Fe, Pb, Cu) | Reduction with carbon (coke) | ZnO + C → Zn + CO |
| Least reactive (Ag, Au) | Found native; no reduction | Gold occurs as free metal |
Watch out for (2)
- Cinnabar is mercury, not copper→ Common ores and their metals
- Aluminium needs electrolysis, not carbon→ Extraction method versus reactivity
Reference tables (2)
Corrosion of common metals4 rows
| Metal | Corrosion product | Colour / behaviour |
|---|---|---|
| Iron | Hydrated iron(III) oxide (rust) | Reddish-brown; flakes off — corrodes rapidly Of the common metals, iron corrodes the fastest — its rust flakes away and exposes fresh metal. |
| Copper | Basic copper carbonate | Green coat (patina) in moist air The green coat on old copper is basic copper carbonate, NOT copper oxide. |
| Aluminium | Aluminium oxide | Thin, protective layer — stops further attack |
| Silver | Silver sulphide | Black tarnish in sulphur-containing air |
Preventing corrosion — galvanization and sacrificial protection4 rows
| Method | What is applied | Why it works |
|---|---|---|
| Galvanization | Thin layer of zinc | Zinc is more reactive — sacrifices itself to protect iron Zinc protects iron even when scratched because it is more electropositive than iron (sacrificial protection). |
| Painting / oiling | Paint or grease film | Keeps air and moisture off the metal |
| Electroplating | Tin or chromium layer | Inert coating barrier |
| Alloying | Mix with Cr, Ni (stainless steel) | Forms a corrosion-resistant alloy |
Watch out for (2)
- Copper goes green, iron goes brown→ Corrosion of common metals
- Zinc protects because it is MORE reactive→ Preventing corrosion — galvanization and sacrificial protection
Reference tables (2)
Common alloys and their composition6 rows
| Alloy | Composition | Note |
|---|---|---|
| Brass | Copper + Zinc | Both metals |
| Bronze | Copper + Tin | Cu + Sn — the bank's favourite composition question |
| Steel | Iron + Carbon | Carbon is a non-metal — the 'alloy with a non-metal' answer Steel is the alloy that contains a NON-METAL (carbon). Brass, bronze and amalgam are metal-only. |
| Stainless steel | Iron + Chromium + Nickel (+ C) | Tin is NOT an essential component Essential components of stainless steel are Fe, Cr and Ni — tin is the odd one out. |
| Amalgam | Mercury + another metal | Mercury-based alloy |
| Solder | Lead + Tin | Low-melting joining alloy |
Special-purpose alloys4 rows
| Alloy | Composition | Special use |
|---|---|---|
| NaK | Sodium + Potassium | Coolant / heat transfer in nuclear reactors Potassium is alloyed with sodium (NaK) to transfer heat in nuclear reactors. |
| Nichrome | Nickel + Chromium | Heating elements (high resistance) |
| Magnalium | Aluminium + Magnesium | Light, strong structural parts |
| Type metal | Lead + Tin + Antimony | Printing type |
Watch out for (3)
- Brass vs bronze — don't swap zinc and tin→ Common alloys and their composition
- Tin is not in stainless steel→ Common alloys and their composition
- NaK coolant uses potassium, not calcium→ Special-purpose alloys
PYQ weightage by concept
9 concepts · 18 PYQs — where the marks actually sit, so you know what to drill first
PYQ weightage by concept
9 concepts · 18 PYQs — where the marks actually sit, so you know what to drill first
| Concept | PYQs | Share |
|---|---|---|
| Reactions with water and alkali-metal trends | 5 | 28% |
| The reactivity series — order of metals | 2 | 11% |
| Metals versus non-metals — the property contrastfoundation | — | — |
| Concept | PYQs | Share |
|---|---|---|
| Common ores and their metals | 1 | 6% |
| Extraction method versus reactivity | 1 | 6% |
| Concept | PYQs | Share |
|---|---|---|
| Preventing corrosion — galvanization and sacrificial protection | 3 | 17% |
| Corrosion of common metals | 2 | 11% |
| Concept | PYQs | Share |
|---|---|---|
| Common alloys and their composition | 3 | 17% |
| Special-purpose alloys | 1 | 6% |
Test yourself on a real paper
Sit a past NDA paper, timed and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.