Extraction of Metals
Learn how we extract metals from ores using reduction and electrolysis
Quick Overview
The extraction method for any metal depends on its position in the reactivity series. More reactive metals require more energy (electrolysis), while less reactive metals can be extracted by reduction with carbon. Here's the landscape:
🔋 Metals Above Carbon
Extracted by electrolysis — Al, Mg, Na, K. Expensive because electricity is required.
⚙️ Metals Below Carbon
Extracted by reduction with C or CO — Fe, Zn, Cu. Cheaper; uses heat and carbon.
💎 Very Unreactive Metals
Found native — Au, Ag, Pt. Already exist as pure elements in the earth.
The Big Idea: Think of the reactivity series as a reactivity ladder. The higher up the ladder a metal is, the harder it is to rip away the oxygen from its ore—so you need a more powerful tool (electrolysis). Lower down the ladder, you can do it with just heat and carbon.
Metals and Ores: The Starting Point
What is an Ore?
An ore is a rock that contains enough of a metal (usually combined with oxygen as an oxide, or with other non-metals) to make extraction economically worthwhile. For example:
- Hematite (Fe₂O₃) — iron ore, contains iron oxide
- Bauxite (Al₂O₃) — aluminium ore, contains aluminium oxide
- Malachite — copper ore, contains copper compounds
Why Extraction is a Reduction Process
Most metal ores are oxides. Extracting the metal means removing the oxygen from the ore. In chemistry, removing oxygen is called reduction. This is the key insight that connects all metal extraction:
The choice of reducing agent (carbon, carbon monoxide, or electricity) depends on the metal's position in the reactivity series.
Native Metals
Some very unreactive metals are found native—meaning they already exist as pure, uncombined elements in the earth. Examples: gold, platinum, silver. These metals are so unreactive that they don't easily combine with oxygen or other elements, so they don't need extracting from oxides—they can be found and refined almost directly.
Practice Question: Why do you think very unreactive metals like gold can be found as native metals, while very reactive metals like potassium are never found native?
The Reactivity Series & Extraction Methods
The reactivity series tells you how vigorously a metal reacts with oxygen and water. It is the single most important guide for determining how a metal should be extracted.
The Key Rule
Metals above carbon in the reactivity series are too reactive to be extracted by heating with carbon. Instead, they must be extracted by electrolysis (using electrical energy). This is expensive, which is why aluminium, despite being so useful, costs more to extract than iron.
Metals below carbon can be extracted by heating with carbon or carbon monoxide. The carbon steals the oxygen from the metal oxide, freeing the metal. This is cheaper.
| Reactivity Series Position |
Extraction Method |
Cost |
Examples |
| Above carbon |
Electrolysis of molten compound |
Expensive |
Al, Mg, Ca, Na, K |
| Below carbon |
Heating with C or CO |
Cheaper |
Fe, Zn, Sn, Cu |