# How do you know the charge of common ions, i.e. nitrate, sulfate, etc?

##### 1 Answer
Jul 11, 2016

Normally, the charge of common ions have to be committed to memory.

#### Explanation:

Sulfates, carbonates, biphosphates, all have $- 2$ charges. Halides all have $- 1$ charges. For metals, the charge derives from the Group number. And of course, the transition metals generally have a ${M}^{2 +}$ identity.

All these charges simply have to be learned. There are not that many, and often you are given a clue.