# Metals

> CIE IGCSE Chemistry · CIE IGCSE Chemistry (0620)
> Source: https://www.owlsprep.com/study/cie-0620-u9-overview/
> Weight: 8-10% of total exam marks across MCQ and structured sections

This unit covers core metal properties, the reactivity series, industrial metal extraction processes, and modification of metals via alloying, linking chemical theory to real-world applications.

**Prerequisites:** [Atomic structure and ionic bonding](https://www.owlsprep.com/study/cie-0620-u3-ionic-bonding/); [Balanced chemical equations and redox reactions](https://www.owlsprep.com/study/cie-0620-u4-redox-reactions/)

## Learning objectives

- Describe the characteristic physical and chemical properties of metals and relate these to their everyday and industrial uses
- Use the reactivity series to predict displacement reactions, corrosion risk, and suitable metal extraction methods
- Explain how alloying modifies metal properties and give examples of common alloys and their specific applications
- Outline key industrial extraction processes for iron and aluminium, including relevant raw materials and chemical reactions

## Unit at a Glance

You will begin by learning the defining physical and chemical properties of pure metals, how mixing metals (or metals with small amounts of non-metals) to form alloys changes these properties, and how property differences determine metal uses across domestic and industrial contexts.

Next, you will master the standard reactivity series of metals, use it to predict displacement reaction outcomes and corrosion behaviour, before applying this knowledge to understand why different metals require vastly different extraction methods from their naturally occurring ores.

Work through the following subtopics in order to build your mastery of this unit:
- [Properties, Uses and Alloys of Metals](https://www.owlsprep.com/study/cie-0620-u9-properties-uses-and-alloys-of/) — Covers characteristic physical/chemical properties of pure metals, common alloy compositions, and links between properties and real-world uses.
- [Reactivity Series and Corrosion](https://www.owlsprep.com/study/cie-0620-u9-reactivity-series-and-corrosion/) — Explains the reactivity series order, displacement reaction predictions, causes of iron rusting, and effective corrosion prevention methods.
- [Extraction of Metals](https://www.owlsprep.com/study/cie-0620-u9-extraction-of-metals/) — Outlines extraction methods for iron and aluminium including full industrial processes, required raw materials, and key redox reactions.

## Common pitfalls

- **Wrong:** Assuming all metals have high melting points (e.g. incorrectly classifying low-melting group 1 metals as non-metals).
  - Why it fails: General metal property rules have clear exceptions: group 1 alkali metals have very low melting points, low density, and are soft enough to cut with a knife.
  - Correct: Memorize common exceptions to general metal property rules, especially for group 1 metals, to avoid errors in property-based classification questions.
- **Wrong:** Using expensive electrolysis to extract low-reactivity metals like copper or iron, wasting significant energy.
  - Why it fails: Extraction method is directly determined by reactivity: only very reactive metals (above carbon in the reactivity series) require electrolysis for extraction.
  - Correct: Always match extraction method to the metal’s position in the reactivity series to select the most efficient, cost-effective process.
- **Wrong:** Using the term 'rusting' to describe corrosion of all metals, including aluminium or zinc.
  - Why it fails: Rusting is a specific oxidation reaction that only affects iron and its alloys (e.g. steel), while other metals corrode via distinct chemical processes.
  - Correct: Use 'rusting' exclusively for iron-based metals, and the general term 'corrosion' for oxidation of all other metal types.

## Cheatsheet

| Name | Key Formula/Rule | Related Subtopic |
| --- | --- | --- |
| General acid-metal reaction | Metal + dilute acid → salt + hydrogen (only applies to metals above H in reactivity series) | Reactivity Series and Corrosion |
| Rusting reaction | $4Fe + 3O_2 + 2H_2O \rightarrow 2Fe_2O_3 \cdot H_2O$ (hydrated iron(III) oxide) | Reactivity Series and Corrosion |
| Displacement reaction rule | A more reactive metal will displace a less reactive metal from its salt solution or metal oxide | Reactivity Series and Corrosion |
| Alloy hardness rule | Alloys are harder than pure metals because irregular atom sizes disrupt the sliding of uniform metal layers | Properties, Uses and Alloys of Metals |
| Blast furnace iron extraction | $Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2$ (key reduction reaction) | Extraction of Metals |
| Aluminium extraction tip | Cryolite is added to aluminium oxide to lower its melting point, reducing energy costs for electrolysis | Extraction of Metals |

## What's next

Kick off your study of this unit by exploring the first subtopic: Properties, Uses and Alloys of Metals, where you will build foundational understanding of core metal characteristics and how alloying expands their practical applications. Once you have mastered all three subtopics in this Metals unit, your next learning step will be the unit on Organic Chemistry, the next core theme in the CIE IGCSE Chemistry syllabus.

- [Organic Chemistry](https://www.owlsprep.com/study/cie-0620-u11-overview/)

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