Naming Chemical Compounds

Compounds can be named by using common names or standard names as proposed by International Union for Pure and Applied Chemistry (IUPAC).

BINARY COMPOUNDS

Binary compounds are the compounds consist of two elements (but not necessarily two atoms).
    1. Naming Binary Ionic Compounds
      2. Binary ionic compounds contain a metal as a positive ion and a non-metal as a negative ion.

      RULES FOR NAMING BINARY IONIC COMPOUNDS

      1. The name starts with the metal and ends with a non-metal.
      2. The name of metallic ion is the name of element itself.
      3. The name of non-metal which form the second part of the name ends up with the suffix “-ide”.
      Examples,
      1. Oxygen→ oxide
      2. Fluorine→ fluoride
      3. Sulphur →sulphide
      4. Bromine→ bromide
      5. Nitrogen→ nitride
      6. Chlorine→ chloride
      7. Hydrogen →hydride

      Examples
      Name the following compounds
      1. CaCl2 Calcium chloride
      2. Mg3N2 Magnesium nitride
      3. Al2O3 Aluminium oxide
    2. Naming binary ionic compound containing metal with variable oxidation states.

    Examples
    Name the following compounds
    1. CuCl2 copper(II) chloride.
    2. PbCl2 lead (II) chloride.
    3. Hg2Cl2 mercury (I) chloride
    4. HgCl2 mercury (II) chloride
    5. CuO copper (II) oxide
    6. Cu2S copper (I) sulphide.

    Name the following compounds
    1. CaO
    2. PbCl4
    3. FeCl3
    4. Fe2O3
    5. AlN
  2. Naming ionic compounds containing Radicals
    3. A radical is the group of atoms that act as one atom but does not exist independently.

    Examples
    1. CaSO4 calcium sulphate
    2. Na3PO4 sodium phosphate.
    3. NaHCO3 sodium hydrogencarbonate
    4. CaCO3 calcium carbonate.
    5. NaOH Sodium hydroxide
  3. Naming Binary Covalent Compounds.

    4. Binary covalent compounds are compounds with two elements usually non-metals.

    Rules for naming covalent compounds

    1. The name of the first element is the name of element itself.
    2. The name of the second element ends up with suffix “-ide”.
    3. Sometimes the number of atoms of each element is indicated by using the following prefixes
    Number of atoms Prefix Prefix used
    1 Mono- Mono-
    2 Di- Di-
    3 Tri- Tri-
    4 Tetra- Tetr-
    5 Penta- Pent-
    6 Hexa - Hex-
    7 Hepta - Hept-
    8Octa - Oct-
    9 Nona - Non-
    10Deca- Dec-

    Note:
    We sometimes omit some parts of the word in the prefixes wehen naming some elements which start with vowels such as oxide. For example tetroxide instead of tetraoxide. But for consonants we use use as indicated "eg. tetrachloride and not tetrchloride"
    Example
    Name the following compounds
    1. CO carbon monoxide.
    2. SF6 sulphur hexafluoride
    3. PCl3 phosphorus trichloride

    Special Cases

    1. Some compounds use common names.

      2. Examples
      Chemical formulaCommon nameNames of covalent compound
      NH3 ammonia nitrogen trihydride
      H2O water dihydrogen monoxide
      PH3 phosphine phosphorus trihydride.

    2. Like metals, most non-metals exhibit variable valencies. Their IUPAC names should therefore include the valency of that element in a compound.

      3. →In this case, the oxidation state of the first element should be calculated and included in the name of the compound. The second non-metal should end up with the suffix “-ide” without stating the number of atoms present.

    Example
    1. CO the oxidation state of carbon is +2 the name of this compound is Carbon (II) oxide.
    2. CO2 Carbon (IV) oxide.
    3. PCl5 Phosphorus (V) chloride.

    Practice

    Name the following chemical compounds
    1. SO2
    2. SO3
    3. P4O10
    4. SiF6

    Name these compounds by using IUPAC system
    1. SO2
    2. P4O10

  4. Naming acids

    1. Names of most acids end up with the suffix “-ic”.
    2. In systematic naming oxy-acids, the oxidation state of the non-oxygen element other than hydrogen must be indicated.
    3. The complete name must end with the word acid.

    Examples
    Chemical formula Systematic name Common name
    H2SO4 Sulphuric (VI) acid Sulphuric acid
    HCl Hydrochloric acid Hydrochloric acid
    H2SO3 Sulphuric (IV) acid Sulphorus acid
    HNO3 Nitric (V) acid Nitric acid
    H3PO4 Phosphoric (V) acid Phosphoric acid
    HNO2 Nitric (III) acid Nitrous acid
    HClO3 Chloric (V) acid Chloric acid
    HClO Chloric (I ) aci hypochlorous
    HClO4 Chloric (VII) acid Perchloric acid
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