Molecular Compounds are formed by two nonmetals that share electron pairs. Sometimes the electrons are not shared equally and are located closer to one of the atoms. The atom with the electrons closer to it has a negative apparent charge or oxidation number. The other atom will have a positive oxidation number.
Naming Molecular Compounds:
Molecular compounds are named using prefixes. Mono- means one, di- means two, tri- means three, tetra- means four, penta- means five. Note: The prefix mono- is never used one the first atom named.
Examples: PCl3 is called Phosphorus trichloride
N2O5 is named Dinitrogen pentaoxide.
NO2 is named Nitrogen dioxide.