Analía Bellizzi – Chemistry Classes

Ronald Reagan High School

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
    1. Mono (never used in the first name)
    2. Di
    3. Tri
    4. Tetra
    5. Penta
    6. Hexa
    7. Hepta
    8. Octa
    9. Nona
    10. 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
  • 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
  • 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)
    • 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