molecular formula

Noun

WordNet 3.0

Noun (1)

a chemical formula based on analysis and molecular weightSynonyms: molecular formula

Webster's Dictionary (GCIDE)

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. [1913 Webster]

2.(Eccl.) A written confession of faith; a formal statement of foctrines. [1913 Webster]

3.(Math.) A rule or principle expressed in algebraic language; as, the binominal formula. [1913 Webster]

4.(Med.) A prescription or recipe for the preparation of a medicinal compound. [1913 Webster]

5.(Chem.) A symbolic expression (by means of letters, figures, etc.) of the constituents or constitution of a compound. [1913 Webster]

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. [1913 Webster]

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]