Question

What is an anion?

Answer 1

An Anion is a negatively charged ion.

Non-metals readily take on electrons in order to fulfill the role of octet and in turn become negatively charged ions.

Fluorine `(1s^2 2s^2 2p^5)` is one electron short of a filled outer orbital and readily takes on an extra electron becoming `(1s^2 2s^2 2p^5)` and a `F^-1` anion .

The polyatomic ion nitrate is a covalent bond between a nitrogen with a +5 charge and three oxygens with -2 charges. This creates a -1 imbalance and makes nitrate an `NO_3^-1` polyatomic anion.