Naming Covalent Compounds
Nomenclature is a set or system of names. The nomenclature that we use in chemistry is based on the IUPAC (International Union of Pure and Applied Chemists) . The following simplified rules can be used to name the most of inorganic compounds.
Naming Simple Covalent Compounds:
Binary Covalent Compounds (only 2 elements form the compound)
- Covalent compounds use prefixes in both names
- Format: PREFIXelement1 PREFIXelement2IDE
- Mono (never used in the first name)
- Di
- Tri
- Tetra
- Penta
- Hexa
- Hepta
- Octa
- Nona
- Deca
- Name the non-metal furthest to the left or to the bottom on the periodic table by its elemental name with the prefix if different than 1
- Name the second non-metal (the more electronegative) by its elemental name with the prefix and the suffix “ide” at the end.
The first non-metal will not change the name, the second non-metal will get the suffix “IDE”
- Acidic Oxides = Non-Metal + Oxygen → Name: Prefix-Non-metal Oxide
- Examples:
- CO2 = Carbon dioxide
- SO2 = Sulfur dioxide
- P2O5 = Diphosphorous Pentoxide
- N2O4= dinitrogen tetroxide
- Examples:
- General Covalent Compounds = Non-Metal + Non-Metal → Name: Prefix-Non-metal Prefix-Non-metal-ide
- Examples:
- SF6 = Sulfur hexafluoride
- P2Cl5 = Phosphorous pentachloride
- CCl4 = Carbon tetrachloride
- Examples:
- Compounds that contain hydrogen = Hydrogen + Non-Metal → Name: Hydrogen Non-metal-ide
- Examples:
- HF = hydrogen fluoride
- HCl = Hydrogen Chloride pentachloride
- H2S = Hydrogen Sulfide (also called Dihydrogen sulfide)
- Examples:
-
- These compounds react with water forming acids. we will cover this in the NAMING ACIDS PAGE.
- There are some exceptions for the following compounds names:
- H2O = Water
- NH3 = Ammonia
- PH3 = Phosphine
- CH4 = Methane