Ions

The key idea

An ion is an atom or molecular entity carrying a net electric charge because its numbers of protons and electrons are not balanced.

Why it matters

Losing electrons gives a positive charge; gaining electrons gives a negative charge. This simple bookkeeping is behind salts, electrochemistry and much of solution chemistry.

A picture to remember

Losing electrons gives a positive charge; gaining electrons gives a negative charge. This simple bookkeeping is behind salts, electrochemistry and much of solution chemistry.