Metals: Reactivity, Rust, and Getting Metals Out of Rocks
Reactivity Ranked: Top of the Series Wins 🥇
Introduction
1. Introduction
Okay, metals. The whole chapter basically runs on one leaderboard: the reactivity series. It ranks metals from "reacts like it's on fire" (potassium at the top) down to "honestly couldn't care less" (gold at the bottom). 🥇
Here's the cheat code: once you know who's higher up the leaderboard, you can predict almost everything. Which metals fizz in acid? Which ones bother to react with water? Which metal kicks another one out of a solution? How do we even get these metals out of the ground? All of it comes back to who's more reactive. This is your fast refresh, not the full textbook: one key idea per section, one quick worked example, and the exact move the marker wants. Let's climb the leaderboard. 🧗
Here's the cheat code: once you know who's higher up the leaderboard, you can predict almost everything. Which metals fizz in acid? Which ones bother to react with water? Which metal kicks another one out of a solution? How do we even get these metals out of the ground? All of it comes back to who's more reactive. This is your fast refresh, not the full textbook: one key idea per section, one quick worked example, and the exact move the marker wants. Let's climb the leaderboard. 🧗
2. What Metals Are Actually Like
Metals have a starter pack of properties: they conduct electricity and heat, they're malleable (you can bend/hammer them), ductile (you can pull them into wire), shiny, dense, and they melt at high temps. Non-metals are basically the opposite: dull, brittle, don't conduct. There's a chemistry tell too: metals make basic oxides, non-metals make acidic oxides. So if something forms a basic oxide and fizzes with acid to give hydrogen, it's a metal. 💯
Key idea🔑 Key idea: Metal = conducts + malleable + makes a basic oxide. Non-metal = the opposite, makes an acidic oxide. 🎯
Worked example
Worked Example: Spot Two Metal Properties
Worked Example: Don't Repeat the Freebie 🎁
Metals are good conductors of heat. State two other properties typical of metals.
- 1"Conducts heat" is already given, so don't reuse it.
- 2Grab two different ones: malleable and good conductor of electricity.
Done. (Shiny, ductile or dense would also score.) ✅
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3. Use the Right Metal for the Job
Two main characters: aluminium and copper. Aluminium is light (low density) and resists corrosion, so it's used for aircraft, power cables and drink cans. Copper is a brilliant conductor and is ductile, so it's used for electrical wiring and pan bases (it also conducts heat well). The exam move: always say the property and why it fits the job. 🛠️
Key idea🔑 Key idea: Aluminium = light + doesn't corrode. Copper = conducts electricity (and heat) really well. Match property → job. ⚡
Worked example
Worked Example: Why Aluminium for Power Cables
Worked Example: True ≠ Reason 🧠
Which explains using aluminium for overhead cables: (1) aluminium is less dense than copper; (2) copper conducts better; (3) aluminium is more reactive?
- 1Cables hang high, so they need to be light → statement 1 works. ✓
- 2Statement 2 is a reason for copper, not aluminium. Statement 3 doesn't help a cable. ✗
So only statement 1: the key property is low density. 🪶
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4. Alloys: Mix Metals, Get Something Tougher
An alloy is a mixture of a metal with other elements (it's a mixture, NOT a compound). Examples: brass = copper + zinc; stainless steel = iron with chromium, nickel and carbon. Learn the syllabus line: alloys can be harder and stronger than the pure metals and are more useful. Stainless steel is used for cutlery because it's hard and resists rusting. In a structure diagram, a pure metal is one size of atom in regular rows; an alloy has different-sized atoms mixed in, so the rows are distorted. 💪
Key idea🔑 Key idea: Alloy = mixture (never a compound). Alloys can be harder and stronger than the pure metal, and more useful. Diagram: different-sized atoms, distorted rows = alloy. 🧱
Worked example
Worked Example: Mixture, Compound or Alloy?
Worked Example: Tick the Right Boxes ✅
18-carat gold is 75% gold + 25% copper, mixed. Which are true: (1) mixture; (2) compound; (3) alloy; (4) conducts electricity?
- 1Metals mixed but not chemically joined → mixture (1 ✓) and alloy (3 ✓), but not a compound (2 ✗).
- 2Still made of metal → conducts (4 ✓).
Answer: 1, 3 and 4. 🥇
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5. The Reactivity Leaderboard
The reactivity series, most reactive first: K Na Ca Mg Al (C) Zn Fe (H) Cu Ag Au. Read it like this: the top three (K, Na, Ca) react with cold water; the middle metals (Mg, Zn, Fe) react with steam but not cold water; the bottom ones (Cu, Ag, Au) don't react with water or acid. Metals above hydrogen fizz in acid to give salt + hydrogen. 🔥
Key idea🔑 Key idea: Cold water → top three. Steam only → middle. No reaction with acid → bottom. The ladder predicts everything. 🪜
Worked example
Worked Example: Rank the Metals
Worked Example: Cold Water Wins 🥤
J: steam + acid, not cold water. K: acid only. L: acid + cold water. M: no acid reaction. Order them, most reactive first.
- 1L reacts with cold water → most reactive. J does steam (middle) → next.
- 2K does acid only → below J. M does nothing → least.
Order: L, J, K, M. 🏁
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6. Reacting with Acids and Water
Two reactions worth memorising. Metal + acid → salt + hydrogen (you see fizzing). Reactive metal + cold water → metal hydroxide + hydrogen. Watch the products: cold water makes a hydroxide, but steam makes an oxide. Mixing those two up is the most common dropped mark in this topic, so lock it in. 💧
Key idea🔑 Key idea: Acid → salt + hydrogen. Cold water → hydroxide + hydrogen. Steam → oxide + hydrogen. Don't swap hydroxide and oxide. 💨
Worked example
Worked Example: Calcium Meets Water
Worked Example: Hydroxide, Not Oxide 🚰
Finish: calcium + water → ? + ?
- 1A reactive metal with cold water makes a hydroxide and hydrogen.
- 2So: calcium + water → calcium hydroxide + hydrogen (). 🚰
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7. Displacement: Reactive Metals Bully the Rest
A more reactive metal displaces a less reactive one from a solution of its salt. Classic: drop zinc into blue copper(II) sulfate and zinc displaces the copper () — the blue fades and copper coats the zinc. So if metal A pushes out metal B, A is higher up the series. It's basically the leaderboard settling a fight. 🥊
Key idea🔑 Key idea: "A displaces B" = "A is more reactive than B". A coating of metal X on metal Y means Y won (Y is more reactive). 🏆
Worked example
Worked Example: Order from Displacement
Worked Example: Chain the Arrows 🔗
P displaces Q from Q's salt. Q displaces R from R's salt. Order them, most reactive first.
- 1P beats Q → P > Q. Q beats R → Q > R.
- 2Chain them: P, Q, R. 🔗
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8. Rust: Iron's Worst Enemy
Rusting is iron corroding, and it needs two things together: water and oxygen. Take either one away and no rust. The rust itself is hydrated iron(III) oxide (memorise that name, it's a free mark). To stop rust, use barrier methods that keep water and oxygen out: painting, greasing (oiling) or coating with plastic. The catch: a barrier only works while it's not scratched. 🛡️
Key idea🔑 Key idea: Rust = water + oxygen → hydrated iron(III) oxide. Barriers (paint, grease, plastic) keep water and oxygen off. 💧
Worked example
Worked Example: Which Nail Rusts?
Worked Example: Remove One Thing Each Time 🧪
Tube 1: nail in water, open to air. Tube 2: nail in dry air, no water. Tube 3: nail in boiled water (no air) under oil. Which rusts?
- 1Rust needs both water and oxygen. Tube 1 has both → rusts. ✓
- 2Tube 2 has no water; tube 3 has no oxygen → neither rusts.
Only tube 1. 🧪
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9. Getting Metals Out of Rocks
Metals are usually stuck to oxygen in an ore, so extracting them means removing the oxygen. The method depends on where the metal sits compared to carbon: below carbon (zinc, iron, copper) → just heat with carbon (cheap, this is how iron is made); above carbon (Na, Ca, Mg, Al) → carbon can't shift the oxygen, so use electrolysis (pricey). Gold? It's so unreactive it's found native (already pure). 🪨
Key idea🔑 Key idea: Above carbon → electrolysis. Below carbon → heat with carbon. Compare the metal to carbon, not hydrogen. ⚡
Worked example
Worked Example: Why Carbon Can't Do Aluminium
Worked Example: Too Reactive for Carbon 🚫
Iron is extracted with carbon, but aluminium by electrolysis. Why can't carbon extract aluminium?
- 1Carbon only works on metals less reactive than carbon.
- 2Aluminium is above carbon = more reactive, so carbon can't remove its oxygen.
So aluminium needs electrolysis. 🚫
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10. Iron in the Blast Furnace
Iron comes from its ore hematite in a blast furnace. The star player is carbon (coke), and it does two things: it burns to give heat (carbon + oxygen → carbon dioxide), and that carbon dioxide reacts with more coke to make carbon monoxide, the gas that actually grabs the oxygen off the ore (iron(III) oxide + carbon monoxide → iron + carbon dioxide). Limestone decomposes in the heat to calcium oxide, which clears out the sandy bits as slag. Word equations are all you need here: at Core, symbol equations for the blast furnace are not required. 🏭
Key idea🔑 Key idea: In the furnace, carbon burns for heat AND makes carbon monoxide, and it's the carbon monoxide that reduces the iron ore. Limestone removes sand as slag. 🔥
Worked example
Worked Example: Why Carbon in the Furnace
Worked Example: Heat Plus the Reducing Gas 🔥
Give two reasons carbon (coke) is used in the blast furnace.
- 1It burns in the hot air and gives out heat to keep the furnace hot.
- 2It makes carbon monoxide, the gas that reduces the iron ore.
Two jobs: fuel for heat, and source of the reducing gas. 🔥
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