Respuesta :

it is meant to distinguish the number of polyatomic ions from the number of atoms in a given polyatomic ion. an example is Ca(NO3)2
In a chemical compound, parenthesis are used to distinguish the number of polyatomic ions from the number of atoms. Such as in the compound calcium nitrate, it is written as [tex] Ca(NO_{3} ) _{2} [/tex]. This means there are two nitrate ions for every one calcium ion.