Flame tests are used in chemistry to identify metals or ions in compounds. They are more useful for some metals than others; particularly for the Group 1 metals, they provide a good way of quickly identifying the metal ion present.
This picture looks at the colour of various metal and metalloid ions that occur during flame tests. Most people probably remember have seen one flame test (often sodium) during an experiment in experimental lesson at school.
To carry out the flame tests, a small amount of the compound being tested will be held in a flame and the colour given off observed. This colour originates from the movement of the electrons in metal ion. When heated, the electrons gain energy, and are « excited » into higher energy levels; however, the electrons occupying these levels is more energetically unstable, and they tend to fall back down to their original energy levels, releasing energy as they do so. This energy is released as light, with the characteristic flame colours of different metal ions due to varying electron transitions.