Final answer:
The numerical value of the second nonmetal in a covalent molecule is indicated by a numerical prefix, and the full name includes the 'ide' suffix after the stem of the element's name.
Step-by-step explanation:
When naming the second nonmetal in a covalent molecule, the numerical value is indicated by a numerical prefix. For instance, in the compound dinitrogen trioxide, the prefix 'di-' indicates two nitrogen atoms, and the prefix 'tri-' indicates three oxygen atoms, hence the chemical formula is N2O3. The naming process involves adding an '-ide' suffix to the stem of the nonmetal element's name. The prefix 'mono-' is not typically used for the first element if there is only one atom of it within the molecule.
The general rule in writing formulas of binary covalent compounds is placing the less electronegative element first, with a few exceptions such as in compounds with carbon, which is always listed first, or hydrogen, which is listed after nitrogen. The use of numerical prefixes allows us to distinguish different molecules that may contain the same elements but in different ratios.