Most metals are found in the Earth's crust as ores—naturally occurring rocks that contain metal compounds (usually oxides, sulfides, or carbonates) in sufficient concentrations to be worth extracting. Only a few unreactive metals, such as gold, are found in their "native" or elemental state. The process of obtaining a pure metal from its ore is called extraction. The IGCSE 0654 Core syllabus requires an understanding of how the ease of extraction relates to the reactivity series and a description of the two primary industrial methods used for iron and aluminium.

The more reactive a metal is, the more strongly it is bonded to other elements in its ore, and the more difficult (and expensive) it is to extract.

(a) Unreactive Metals (e.g., Gold, Silver)

These metals are found at the bottom of the reactivity series. They do not readily form compounds and are often found as native metals in the ground. They require only physical separation from the surrounding rock.

(b) Moderately Reactive Metals (e.g., Zinc, Iron)

Metals situated between aluminium and hydrogen in the reactivity series can be extracted by reduction with carbon (or carbon monoxide). Because carbon is more reactive than these metals, it can "steal" the oxygen from the metal oxide.

• The Principle: Metal Oxide + Carbon $\rightarrow$ Metal + Carbon Dioxide

(c) Very Reactive Metals (e.g., Aluminium, Potassium)

Metals at the top of the reactivity series are much more reactive than carbon. Carbon cannot reduce their oxides. Therefore, these metals must be extracted using electrolysis—a process that uses massive amounts of electrical energy to break the incredibly strong chemical bonds.

Iron is extracted from its main ore, hematite (which contains iron(III) oxide, $Fe_2O_3$).

• Method: Chemical reduction in a blast furnace.
• The Reducing Agent: Carbon (in the form of coke) is burned to produce carbon monoxide ($CO$).
• The Reaction: The carbon monoxide reacts with the iron(III) oxide, removing the oxygen to leave liquid iron.

Aluminium is extracted from its main ore, bauxite (which contains aluminium oxide, $Al_2O_3$).

• Method: Electrolysis.
• The Process: The bauxite is first purified to obtain pure aluminium oxide. Because aluminium oxide has a very high melting point, it is dissolved in molten cryolite to lower the temperature. A massive direct current is then passed through the liquid, decomposing the oxide into molten aluminium metal at the cathode and oxygen gas at the anode.
• Cost: This process is significantly more expensive than the blast furnace because of the enormous quantity of electricity required.

The extraction of metals is a direct application of the reactivity series. By understanding the strength of the chemical bonds within ores, industrial chemists can determine the most efficient and cost-effective method for recovery. While carbon reduction remains the backbone of the iron industry, the more reactive metals of the modern age—like aluminium—demand the more intensive power of electrolysis.