- As you move further down group one, the outer shell of electrons becomes further and further away from the nucleus.
- This means that in an atom of an element further down the group, the negative electron in the outer shell is less attracted to the positive nucleus than in an atom of an element higher up the group.
- This means that those elements lower down the group are much more able to give up their outer electron in a chemical reaction
- Therefore, they react more easily and more vigorously