The alkali metals group

Group 1 of the periodic table contains the alkali metals. They all have a low density and can float on water, they have low melting points and are very soft - you can cut them with a knife. They are however, extremely reactive.

The following video demonstrates the violent nature of the chemical reactions of the alkali series of metals with water.

The alkali metals react violently with water. The intensity of the reaction increases as you move down the group through the series from lithium to sodium to potassium and through to rubidium and caesium.