group 1 gets more reactive as you move down the group as it is easier to lose electrons and there is less pull from the nucleus to keep them there.
All have 1 electron in the outer shell.
Alkali metals are very unstable and react vigorously even with water.
Melting points and boiling points as you go down the group
in order to react group 1 metals only have to lose 1 electron.
Group 1 metals form +1 ions.
Ionic compounds are generally white solids and dissolve in water to form colourless solutions,
When a group 1 metal donates an electron to a group 7 metal they form an ionic compound. They have opposite charges and are attracted to each other by electrostatic forces which we call an ionic bond.
When an alkali metal reacts with water it is vigorous and forms a metal hydroxide + hydrogen gas.
When reacted with chlorine they form a metal chloride
When alkali metals react with oxygen they form metal oxides