Reactivity of Group 1 increases when go down the group.
- When an alkali metal atom reacts, it loses an electron to form a singly positively charged ion which is a stable noble gases electron arrangement.
- When go down the group, the atomic radius gets bigger due to an extra filled electron shell and the outer electron is further and further away from the nucleus.
- Therefore the outer electron is less strongly held by the positive nucleus as the attractive force is decreased.
- As a result, the outer electron is more easily lost and react more vigorously.
Reaction of Group 1 with water