Give the name or chemical formula, as appropriate, for each of the following binary molecular substances: (a) SF6, (b) IF5, (c) XeO3, (d) dinitrogen tetroxide, (e) hydrogen cyanide, (f) tetraphosphorus hexasulfide.
Answer
Binary Molecular Compounds: Names and Formulas with Explanations
Binary molecular compounds are composed of two different nonmetals. Their names are based on the number of atoms present using Greek prefixes (mono-, di-, tri-, etc.). Let’s break down each case below:
(a) SF6
Name: Sulfur hexafluoride
Explanation: One sulfur (no “mono” needed for the first element) and six fluorine atoms → “hexafluoride”.
(b) IF5
Name: Iodine pentafluoride
Explanation: One iodine atom and five fluorine atoms → “pentafluoride”.
(c) XeO3
Name: Xenon trioxide
Explanation: One xenon atom and three oxygen atoms → “trioxide”.
(d) Dinitrogen tetroxide
Formula: N2O4
Explanation: “Di” means two nitrogen atoms, “tetra” means four oxygen atoms.
(e) Hydrogen cyanide
Formula: HCN
Explanation: Although it contains three elements, HCN is often treated as a binary compound in common naming. It’s composed of hydrogen and the polyatomic group cyanide (CN).
(f) Tetraphosphorus hexasulfide
Formula: P4S6
Explanation: “Tetra” means four phosphorus atoms, “hexa” means six sulfur atoms.
Note: Prefixes are only used for molecular compounds (nonmetal + nonmetal) and not for ionic compounds.