Elements that are in groups of two or more and have the same charge are polyatomic ions. They exist to help bond together with other polyatomic ions and generally work to form complex compounds.
The most common example of a polyatomic ion is the hydroxide ion. It is an ion in which the oxygen and the hydrogen atoms are bonded together and work together to help each other form more complex bonds with other atoms. Elements that are in a polyatomic ion group always function as if they were a single ion and only carry a charge that a single ion would carry. They are generally not much bigger than a single element and do not take up much more space than a single one typically would.
They are generally around a neutral type of charge and function as the conjugate as an acid or a base, depending on what the ion needs. They can often change their function from an acid to a base because they are a combination of two elemental substances. They are the only type of cells in the universe that are able to easily switch between being acidic and alkaline without a major chemical process. They are able to do this to help the neutral ions that they stay around and are designed to help.