Naming Covalent Molecules
Rules for Naming Covalent
Molecules
The first element in the formula is
named using the original element
name
 The second element in the formula is
named but using –ide ending
 Prefixes indicate the number of atoms
of each element (mono is never used
for the first element)

Prefixes
 Mono
 Di
-1
–2
 Tri -3
 Tetra – 4
 Penta – 5
 Hexa
–6
 Hepta – 7
 Octa – 8
 Nano – 9
 Deca – 10
Examples
P2O5
CO
= diphosphorus
pentoxide
= carbon monoxide