Flame tests for metal ions
Different Shiny element that is a good conductor of electricity and heat, and which forms basic oxides.Electrically charged particle, formed when an atom or molecule gains or loses electrons. produce different flame colours when they are heated strongly. This is the basis of A qualitative identification technique where samples are heated and the metal ions present are identified by characteristic flame colours.. To carry out a flame test:
- dip a clean wire loop into a sample of the compound being tested
- put the loop into the edge of the blue flame from a Bunsen burner
- observe and record the flame colour produced
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 present | Flame test colour |
| Lithium, Li+ | Red |
| Sodium, Na+ | Yellow |
| Potassium, K+ | Lilac |
| Calcium, Ca2+ | Orange-red |
| Copper, Cu2+ | Green-blue |
| Ion present | Lithium, Li+ |
|---|---|
| Flame test colour | Red |
| Ion present | Sodium, Na+ |
|---|---|
| Flame test colour | Yellow |
| Ion present | Potassium, K+ |
|---|---|
| Flame test colour | Lilac |
| Ion present | Calcium, Ca2+ |
|---|---|
| Flame test colour | Orange-red |
| Ion present | Copper, Cu2+ |
|---|---|
| Flame test colour | Green-blue |
Question
A sample of an ionic compound produces an orange-red flame test colour. Identify the metal ion present.
The metal ion is calcium, Ca2+.
