Why are group 1 elements more reactive as you go down the group?

Group 1 elements display similar properties as they all only have a single electron on their outer shell. They make up the first column of the periodic table and are ordered in ascending weight from top to bottom. They react by giving away their single outer electron to another element forming an ionic bond, the heavier elements further down the group are more likely to do this for two reasons. They have a greater atomic number so more electrons - this means that the outer electrons are further away from the nucleus, so the electrons have a weaker electrostatic attraction to the protons in the nucleus so are more likely to be lost More electrons means that there are more shells of electrons greater shielding between the outer electrons and nucleus which further weakens this electrostatic attraction