Derivation and Use of a Total-Bonds Equation

The total number of bonds in a covalent compound is determined by the numbers and kinds of atoms in its molecular formula. An equation is derived for hydrocarbons on the basis that the number of bonds in a structure equals the number of bonds in the corresponding saturated, acyclic compound less its bond deficiency (i.e., the index of hydrogen deficiency). For a hydrocarbon, the number of bonds equals twice the number of carbon atoms plus half of the hydrogen atoms in the molecular formula. A general equation is then derived for any covalent compound on the same basis. The number of bonds equals one-half the sum of each kind of atom in the formula times its valence. The general equation is applicable to both inorganic and organic compounds, including hydrocarbons. The use of the general equation in concert with bond deficiency is exemplified.