Group 1 and Group 7

The idea

Group 1 alkali metals react with water to form a metal hydroxide and hydrogen; they become more reactive down the group because the outer electron is further from the nucleus and more easily lost. Group 7 halogens are non-metals with coloured vapours made of diatomic molecules; they become less reactive down the group because it is harder to gain an electron. A more reactive halogen displaces a less reactive one from a solution of its salt.

1. Write metal + water → metal hydroxide + hydrogen.
2. State the trend and explain it with electron distance.
3. For displacement, compare reactivity.

Watch out Reactivity increases down Group 1 but decreases down Group 7.