To name a covalent bond first, write the name of the central atom next add the prefix for the amount of the second atom. Finally, write the name of the second atom with the ending ide so CO2 would be Carbon dioxide, CH4 would be Carbon tetrahydride. However, if the center atom has a subscript we would write the respective prefix, for example, P3O5 is triphosphorus pentoxide because there are 3 phosphorus.