Define cation and anion. In which case are electrons gained? Lost?

Explanation:

A cation is a positively charged ion.

An anion is a negatively charged ion.

In an atom, the balance between the number of protons and electrons determine whether they become an anion or cation.

Protons are positively charged particles.

Electrons are negatively charged

 When an atom gains electrons, the number of electrons becomes more than that of protons. This leaves a net negative charge on the atom and it makes an anion.

 When an atom loses electrons, the number of protons becomes more than that of electrons. This leaves a net positive charge on the atom and makes a cation.