Group 1 metals, such as potassium, sodium and lithium, react with water to produce a metal hydroxide and hydrogen. For example:
lithium + water → lithium hydroxide + hydrogen
2Li (s) + 2H₂O (l) → 2LiOH (aq) + H₂ (g)
The observations for this reaction of lithium and water are:
- Lithium floats and moves around on the water
- Lithium disappears
The reactions of sodium or potassium and water are somewhat similar, giving those observations and producing a metal hydroxide and water.
This similarity in reactions provides evidence that the 3 metals are in the same family of elements (group of the Periodic Table).