Naming Covalent Compounds
Naming molecular compounds is similar to naming ionic compounds in that we treat the first element as if it is a cation, while the second element is an anion. This means the name of the first element is what it is in the periodic table, while for the second element, we change the ending to -ide.
A reminder that a molecule is a group of two or more atoms held together by covalent bonds. Covalent bonds are usually formed between nonmetals. For example, Cl2, CH4, NH3, CO2.
One difference with naming ionic compounds though is that we add prefixes to denote the number of atoms in the molecule (see table to the right).
SF6 - sulfur hexafluoride
NCl3 - nitrogen trichloride
N2O3 - dinitrogen trioxide
Mono- is never used for naming the first atom in a covalent compound.
Prefixes are usually not used for compounds containing a metal.
Compounds containing hydrogen usually do not have prefixes in their name; instead, they are named using common nomenclature (Examples: NaH - sodium hydride; CH4 - methane).
