Atomic Charge

Since the number of protons (positive charges) always equals the number of electrons (negative charges) in an atom, positive charges equal negative charges and atoms in the elemental state have no charge. Only when an atom takes an electron from another atom does the particle become charged. This charged form of the atom is known as an ion.

Positively charged ions are called cations, and negatively charged ions are called anions. For instance, when chlorine accepts an electron from sodium, the sodium ion that is formed will have one more proton than electrons. It will therefore have a positive charge and be called a cation. The chlorine (or chloride) ion will have one more electron than protons. It will take on a negative charge and be called an anion. The compound formed by this transfer of electrons is sodium chloride or table salt, which is nothing like the highly reactive sodium or extremely poisonous chlorine from which it was formed.