Flame tests for metal ions

Different metal ions produce different flame colours when they are heated strongly. This is the basis of flame tests. To carry out a flame test:

  1. dip a clean wire loop into a sample of the compound being tested
  2. put the loop into the edge of the blue flame from a Bunsen burner
  3. observe and record the flame colour produced
A sample is held in a Bunsen burner flame and burns red.Carrying out a flame test

The table shows the flame test colours for five common metal ions. The same colours are obtained whether the test compound is in the solid state or dissolved in water.

Ion presentFlame test colour
Lithium, Li+Red
Sodium, Na+Yellow
Potassium, K+Lilac
Calcium, Ca2+Orange-red
Copper, Cu2+Green-blue

A sample of an ionic compound produces an orange-red flame test colour. Identify the metal ion present.

The metal ion is calcium, Ca2+.

Each metal ion produces a different flame test colour.