- they are in group 1
- really reactive
- soft solids at room temperature
- low melting and boiling points (this decreases as it goes down the group)
- low densities - so lithium, sodium and potassium float on water
- they all react with air and water (reaction with water produces hydrogen gas and a metal hydroxide that is a strong alkali)
- they all have one electron in their outer shell, and lose this electron in reactions toform ionic compounds in which their ions have a single positive charge, e.g. Na+
- the group 1 elements get more reactive going down the group.