What is an element?
An element is a pure substance made of only one kind of atom. It cannot be broken down into a simpler substance by ordinary chemical means. There are more than 100 known elements, such as oxygen (O), gold (Au), iron (Fe) and carbon (C). Each element has its own chemical symbol of one or two letters.
Key idea
An element contains only one type of atom and cannot be split into simpler substances by chemical methods.
The Periodic Table
The Periodic Table is a chart that arranges all the elements in an orderly way. Scientists arrange elements by their properties so that similar elements are grouped together. This makes it easier to study and predict how elements behave. On the table, most elements are metals, fewer are non-metals, and a few in between are called metalloids (semi-metals).
Metals and non-metals
Elements are commonly classified into metals and non-metals by comparing their properties.
| Property | Metals | Non-metals |
|---|---|---|
| Shiny? | Usually shiny | Usually dull |
| Conduct electricity? | Good conductors | Poor conductors |
| State at room temp. | Mostly solid | Solid, liquid or gas |
| Example | Iron, copper | Oxygen, sulphur |
Example
Copper is a metal used in electrical wires because it conducts electricity well. Oxygen is a non-metal gas that we breathe.
Remember
- An element is made of only one kind of atom.
- Each element has a chemical symbol.
- The Periodic Table arranges elements by their properties.
- Metals are shiny and conduct electricity; non-metals usually do not.