Ions are atoms with a positive or negative charge.
Explanation:
Ions are atoms or molecules that, when subjected to the phenomenon of ionization, gain or lose electrons, ceasing to be neutral and acquiring an electric charge.
The charge that atoms or molecules possess can be positive —if it has lost electrons— or negative when it acquires electrons. The negatively charged particle is called anion, and when it is positively charged cation.
The other options are not correct because of:
<em>There are usually as many or more neutrons than protons.
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<em>Uncharged atoms are neutral.
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<em>The number of protons or neutrons does not affect the electric charge of the atom.</em>
<em>Atoms that joined in fixed proportions can form molecules.</em>
