molecular formula

3 definitions found

molecular formula - Collaborative International Dictionary of English v.0.48 :

  Formula \For"mu*la\, n.; pl. E. Formulas, L. Formul[ae].
     [L., dim. of forma form, model. SeeForm, n.]
     1. A prescribed or set form; an established rule; a fixed or
        conventional method in which anything is to be done,
        arranged, or said.
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     2. (Eccl.) A written confession of faith; a formal statement
        of foctrines.
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     3. (Math.) A rule or principle expressed in algebraic
        language; as, the binominal formula.
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     4. (Med.) A prescription or recipe for the preparation of a
        medicinal compound.
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     5. (Chem.) A symbolic expression (by means of letters,
        figures, etc.) of the constituents or constitution of a
        compound.
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     Note: Chemical formul[ae] consist of the abbreviations of the
           names of the elements, with a small figure at the lower
           right hand, to denote the number of atoms of each
           element contained.
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     Empirical formula (Chem.), an expression which gives the
        simple proportion of the constituents; as, the empirical
        formula of acetic acid is C2H4O2.
  
     Graphic formula, Rational formula (Chem.), an expression
        of the constitution, and in a limited sense of the
        structure, of a compound, by the grouping of its atoms or
        radicals; as, a rational formula of acetic acid is
        CH3.(C:O).OH; -- called also structural formula,
        constitutional formula, etc. See also the formula of
        Benzene nucleus, under Benzene.
  
     Molecular formula (Chem.), a formula indicating the
        supposed molecular constitution of a compound.
        [1913 Webster]

  molecular formula \mo*lec"u*lar form"u*la\, n. (Chem.)
     An expression representing the composition of elements in a
     chemical substance, commonly consisting of a series of
     letters and numbers comprising the atomic symbols of each
     element present in a compound followed by the number of atoms
     of that element present in one molecule of the substance.
     Thus the molecular formula for common alcohol (ethyl alcohol)
     is C2H6O, meaning that each molecule contains two carbon
     atoms, six hydrogen atoms, and one oxygen atom. The molecular
     formula may be written to provide some indication of the
     actual structure of the molecule, in which case structural
     units may be written separately. Thus, ethyl alcohol can also
     be written as CH3.CH2.OH or CH3-CH2-OH, in which the
     period or dash between functional groups indicates a single
     bond between the principle atoms of each group. This formula
     shows that in ethyl alcohol, the carbon of a methyl group
     (CH3-) is attached to the carbon of a methylene group
     (-CH2-), which is attached to the oxygen of a hydroxyl
     group (-OH). A structural formula is a graphical
     depiction of the relative positions of atoms in a molecule,
     and may be very complicated.
     [PJC]

molecular formula - WordNet (r) 2.1 (2005) :

  molecular formula
      n 1: a chemical formula based on analysis and molecular weight