Here's why:

* Atoms: Normally, atoms have an equal number of protons (positive charge) and electrons (negative charge). This makes them electrically neutral.

* Ions: When an atom gains or loses electrons, it becomes an ion.

* Anions: Anions are negatively charged ions formed when an atom gains one or more electrons. This results in more electrons than protons.

* Cations: Cations are positively charged ions formed when an atom loses one or more electrons. This results in fewer electrons than protons.

Example:

A chloride ion (Cl-) has 18 electrons and 17 protons, giving it a net negative charge.