Common types of formula used to represent a chemical compound include molecular formulas, empirical formulas and structural formulas. Condensed structural formulas, which are derived from structural formulas, are also utilized to convey more detailed features of a compound.
In chemistry, compounds are pure substances containing atoms of two or more elements that are chemically bonded in definite proportions. Chemical formulas are designed to provide information about compounds, particularly molecular compounds, in an easy to understand format.
A molecular formula, also known as true formula, is the typical representation of a chemical compound. This formula is written as a single line comprising the symbols of the elements present in the compound and the number of atoms for each element, which are denoted by subscripts placed to the left of the corresponding element. For example, the molecular formula for water is written as H2O. This means that two hydrogen atoms chemically combine with one oxygen atom to form one molecule of water.
An empirical formula describes the simplest whole-number ratio of atoms in a molecular compound. For example, the empirical formula CH2O shows the smallest atomic proportion of 1 C is to 2 H is to 1 O, or 1:2:1. In some cases, the empirical and molecular formulas are the same. In other situations, the actual chemical formula is a multiple of the atomic ratio given in an empirical formula.
A structural formula is a graphical depiction of a compound. It illustrates the individual atoms, the bonding orientation and the type of chemical bonds between atoms. A condensed structural formula is a linear representation of the same characteristics exhibited by a structural formula. For instance, the structural formula of hexane can be expressed in its condensed form using CH3CH2CH2CH2CH2CH3.