How are the anions in all types of binary compounds similar?

Always negative with the same charge, come second in the formula

Explanation:

A binary compound is a compound that is made up of two elements. For example sodium chloride (NaCl) is made up of element sodium and chlorine. In a binary compound, there may or may not be more than one of each element. For example in NaCl, there is one atom of sodium and one atom of chlorine, while in MgCl2, there is one atom of magnesium and two atoms of chlorine. In binary compounds there is cations and anions, cations always come first in the formula and carry positive charge, while anions are always negative with the same charge and also come second in the formula.