Group 1 metals all have one outer electron, which is responisble for their properties. As you go down the group:
- the metals become more reactive. This is due to the increased number of electron shells which means the outer electron is further from the nucleus so it is more easily lost.
-the melting and boiling points of the metals decrease.
Other general reactions of alkali metals include:
-they all react with water to form metal hydroxides (aquous state) and hydrogen gas.
-they all form ionic compounds with non-metals. They lose their outer electron, becoming 1+ ions whilst the non-metal gains the electron becoming a 1- ions.