Final answer:
When listing nonmetal elements in a molecular compound, the less electronegative element is generally first, and prefixes indicate the number of atoms. Exceptions include carbon always being first, and hydrogen following nitrogen. The prefixes are adjusted when the name of the second element begins with a vowel.
Step-by-step explanation:
The order of listing nonmetal elements in a chemical formula is determined by several guidelines. Generally, the less electronegative element is written first, with a few exceptions, such as carbon, which always comes first, and hydrogen, which is listed after nitrogen in compounds like NH3.
When dealing with binary nonmetal compounds, common nonmetals are ordered as C, P, N, H, S, I, Br, Cl, O, F. For nomenclature using the prefix system, prefixes are added to elements to indicate the number of atoms present, but the prefix 'mono' is not used for the first element if only one atom is present, and the 'a' or 'o' at the end of a prefix is dropped if the element's name begins with a vowel.
When naming molecular compounds, the second element is named using the root of the element plus the suffix 'ide.' In the case of hydrogen, however, it is generally listed first, such as in dihydrogen monosulfide (H2S).