Pure metal

A pure metal is a metal made up of identical atoms of one element, arranged in orderly layers. Because those layers can slide over one another when a force is applied, a pure metal is soft and easily bent or shaped. Malay: logam tulen · Chinese: 纯金属.

The softness follows directly from the neat arrangement. In a pure metal every atom is the same size, so the layers are smooth and regular and there is nothing to stop one layer gliding past the next. This makes pure metals malleable, so they can be hammered into shape, and ductile, so they can be drawn into wire. The same property is a drawback where strength is needed, which is the reason pure metals are so often turned into alloys before use. Understanding the pure metal is therefore the starting point for understanding why alloying works.

Example. Pure gold is soft enough to scratch and dent, so jewellery is usually made from gold alloyed with copper or silver. Pure iron and pure aluminium are also relatively soft, and both are strengthened by alloying before being used in construction or aircraft.

Confusion to avoid. Do not confuse a pure metal with an alloy. A pure metal has identical atoms and slides easily, so it is soft; an alloy has atoms of different sizes mixed in, which block the sliding and make it harder. The two are the paired terms of this topic.

When you compare a pure metal with its alloy, always begin with the pure metal: identical atoms, regular layers, easy sliding, and therefore softness. Setting that baseline first makes the reason for the alloy’s greater hardness follow naturally in the next sentence, and it stops the two descriptions from becoming tangled together in a rushed answer.

Describing the layers of identical atoms that slide is the model SPM Chemistry expects when it asks you to compare a pure metal with its alloy.