Brass
Summary: Brass is an alloy of copper and zinc. It is harder, stronger, and more corrosion-resistant than pure copper. Used for musical instruments, door handles, taps, and electrical connectors. Tags: igcse chemistry metals alloy Created: 2026-07-14 Last Updated: 2026-07-23
What Is Brass?
Brass is an alloy — a mixture of:
- Copper (Cu) — ~70%
- Zinc (Zn) — ~30%
(Proportions can vary depending on the desired properties — e.g. 60/40 brass, 70/30 brass.)
Properties
| Property | Description | Reason |
|---|---|---|
| Harder than copper | More resistant to wear | Zn atoms are a different size, disrupting the Cu lattice |
| Stronger than copper | Higher tensile strength | Layers of atoms cannot slide easily |
| Corrosion resistant | Does not rust; tarnishes slowly | Copper naturally forms a protective patina |
| Malleable and ductile | Can be shaped and drawn into wires | Metallic bonding is retained |
| Golden appearance | Attractive colour | The zinc lightens copper’s reddish colour |
| Good acoustic properties | Rings when struck | Used for musical instruments |
| Antibacterial | Kills microbes on contact | Copper ions are naturally antimicrobial |
Why Brass Is Harder Than Pure Copper
See Alloy for the full explanation.
Pure copper has a regular arrangement of identical-sized atoms in layers. When a force is applied, the layers slide over each other → copper is relatively soft.
In brass, zinc atoms are a different size from copper atoms. These differently-sized atoms disrupt the regular layers, preventing them from sliding past each other. This makes brass harder and stronger than pure copper while retaining useful malleability.
Uses of Brass
| Use | Property Exploited |
|---|---|
| Musical instruments (trumpets, trombones, horns) | Acoustic resonance + malleability + attractive appearance |
| Door handles and knobs | Hardness + corrosion resistance + golden appearance |
| Water taps and plumbing fittings | Corrosion resistance + malleability |
| Electrical connectors and plugs | Good electrical conductivity + corrosion resistance |
| Decorative items (statues, ornaments) | Attractive gold-like colour + workability |
| Locks and keys | Hardness + wear resistance |
| Ammunition casings | Malleability (expands to seal chamber) + corrosion resistance |
Comparison: Brass vs Copper vs Bronze
| Material | Composition | Hardness | Colour | Key Uses |
|---|---|---|---|---|
| Pure copper | Cu | Soft | Reddish-brown | Electrical wiring |
| Brass | Cu + Zn | Harder than Cu | Golden-yellow | Instruments, fittings |
| Bronze | Cu + Sn | Harder than brass | Brown-red | Statues, bearings, coins |
Key Facts
- Brass = copper + zinc
- Harder and stronger than pure copper because different sized atoms disrupt layer sliding
- Golden-yellow colour — attractive for decorative uses
- Corrosion-resistant and antimicrobial
- Good conductor of electricity (not as good as pure copper but adequate for connectors)
- Key IGCSE example (along with stainless steel) of how alloying improves properties