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Covalent Formulas and Nomenclature

Key Questions

  • For some background information, a covalent bond is a bond in which two or more elements SHARE electrons to become stable. In retrospect, ionic compounds TRANSFER electrons to make ions and become stable.

    Covalent formulas or covalent molecules are compounds that only (for simplicity) contain NON-METALS.

    For example, potassium chloride, KCl NOT covalent as it contains a metal. However, if you were to analyse something like NO2, this IS covalent as it contains two non metals.

    Examples of covalent molecules:
    H2O
    N2F
    NH3
    FO

  • The empirical formula is the lowest term ratio of the atoms found in a molecule.

    An example would be the empirical formula for a carbohydrate is
    #CH_2O#
    one carbon for two hydrogens for one oxygen

    The carbohydrate glucose has a formula of
    #C_6H_12O_6#
    Notice that the ratio is 1 C to 2 H to 1 O.

    For the alkane group of hydrocarbons the molecular formulas are

    Ethane #C_2H_6#
    Propane #C_3H_8#
    Butane #C_4H_10#

    In each of these molecules the molecular formula can be determines from a base formula of
    #C_nH_(2n+2)#
    This is the empirical formula for all alkanes.

    Here is a video which discusses how to calculate an empirical formula.

    video from: Noel Pauller

    I hope this was helpful.
    SMARTERTEACHER

  • Answer:

    There are a number of things to consider. I'll focus on naming binary molecular compounds. (Just two elements)

    Explanation:

    1. Must include two non-metallic elements
    2. Name of second element has name change to use "ide" ending
    3. First element needs no prefix if there is only one
    4. First element needs a prefix if there are more than two of that element
    5. Second element always needs a prefix

    Prefixes:
    1 - mono
    2 - di
    3 - tri
    4 - tetra
    5 - penta
    6 - hexa
    7 - hepta
    8 - octa
    9 - nona
    10 - deca

    This video discusses how to name binary molecular compounds which have covalent bonding.

    Hope this helps!

Questions