Question

What is the formula for calcium hydroxide?

Answer 1

Calcium is from Group 2 and commonly forms the `Ca^(2+)` ion. Hydroxide ion, `HO^-`, is singly, negatively charged.

Explanation:

To make a neutral species, we simply balance the charges. To balance the charge of the metal ion, `Ca^(2+)`, we need 2 hydroxide ions, `2xxOH^-`.

We get the formula `Ca(OH)_2`. Capisce?

Note that once you know the formula for calcium hydroxide, you know the formula for the hydroxides of ALL the Group 2 metals, i.e. `Ba(OH)_2`, `Sr(OH)_2`. Are you with me?