GCSE SCIENCE CHEMISTRY HIGH SCHOOL - Alkali Metals - Lithium - Sodium - Potassium - Reaction with Oxygen - Burning - Flame Colour

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The Alkali Metals - Reaction with Oxygen (burning in air).

Lithium, sodium and potassium will all burn in air.

Sodium burns in air with an orange flame to form sodium oxide.
Sodium oxide is alkaline.
sodium + oxygen sodium oxide.
4Na_(s) + O_2(g) 2Na₂O_(s)

Similarly, lithium and potassium will burn in air
to give the corresponding alkaline oxides.

Lithium burns in air with a red flame to form lithium oxide.
lithium + oxygen lithium oxide.
4Li_(s) + O_2(g) 2Li₂O_(s)

Potassium burns in air with a lilac flame to form potassium oxide.
potassium + oxygen potassium oxide.
4K_(s) + O_2(g) 2K₂O_(s)

All of the alkaline oxides formed are white powders
which will dissolve in water to form strongly alkaline hydroxides.