See the links for a summary of naming covalent and ionic compounds. Actually contrary to what these links say the method of bonding does not actualy affect the way compounds are named. Lets take to simple examples, FeCl3 and PCl3 the first ionic and the second covalent.
Iron trichloride, could be called iron(III) chloride (historically called ferric chloride)
Phosphorus trichloride could be called phosphorus(III) chloride, or even trichloridophosphane following latest IUPAC definition.
Atoms in molecular compounds not only can but must share electrons, in order to form the covalent bonds that hold molecular compounds together!
The covalent name of C2H6 is ethane.
The covalent compound name for C3N4 is tricyanogen.
The covalent bond name for B2Si would be hepta. This is known to be the short term for it.
Sulfur trioxide
The name for the covalent compound CH4 is methane.
The name of the covalent compound CH4 is methane.
The covalent compound name for SeF2 is selenium difluoride.
The name of the covalent compound XeO3 is xenon trioxide.
The name for the covalent compound IF7 is iodine heptafluoride.
The covalent compound name for SCl2 is sulfur dichloride.
Fe3N2 is ferric nitride, and it is ionic, not covalent.