2.6    describe the reactions of these elements with water and understand that the reactions provide a basis for their recognition as a family of elements

All the Alkali Metals react in a similar way with water, producing hydrogen gas and a solution of the metal hydroxide, which is strongly alkaline (pH around 14).

Lithium	Metal floats and moves around, but does not melt. Bubbles of hydrogen gas are seen (steady fizzing / effervescence) The metal gets smaller and smaller and eventually disappears A colourless, alkaline solution of lithium hydroxide is left.
Sodium	Metal floats and moves around rapidly, forming a molten sphere A white trail is left behind where the metal has been Bubbles of hydrogen gas are seen (rapid fizzing / effervescence) The metal gets smaller and smaller and eventually disappears A colourless, alkaline solution of sodium hydroxide is left.
Potassium	Metal floats, melts and whizzes around rapidly The hydrogen gas is given off very rapidly and burns with a lilac flame Metal often explodes A colourless, alkaline solution of potassium hydroxide is left.

Example equation:        sodium  +  water   ®  sodium hydroxide  +  hydrogen

2Na(s)  +  2H2O(l) ®   2NaOH(aq)   +   H2(g)

Try to remember that it’s the metal HYDROXIDE that forms (not the metal oxide).