Image credit: Freepik
Image credit: Freepik

A chemical formula is a scientific code that depicts a substance’s chemical composition. In other words, the formula gives out the number of atoms there are in a particular molecule or compound. It usually comprises numbers, alphabets, brackets, dashes, signs, etc., which also throw light on the constituent’s quantity and arrangement.

For instance, the chemical formula for water is H2O, indicating that a water molecule has two hydrogen atoms and a single oxygen atom. Some chemical formulas could have brackets. For example, Mg(OH)2 is the chemical formula for magnesium hydroxide. The number 2 to the right of the closing bracket indicates there are two oxygen (O) and two hydrogen (H) atoms.

A chemical formula is a universal language. In other words, the formula is not translated into different languages. Japanese, Russians, Indians, etc. use the same chemical formula as the Americans, English, and people from other parts of the world. Also, the formula always incorporates symbols in capital letters. For example, carbon is denoted as ‘C’ and not ‘c’. Similarly, hydrogen would always be written as ‘H’ and not ‘h’.

Types of Chemical Formulas

There are different types of chemical formulas, which are:

  • Molecular: A molecular formula, also called true formula, denotes the number of various elements residing in a compound’s molecule. The elements are represented with their periodic table symbols, and a subscript is used to indicate the atom count. A subscript is basically a number positioned to the element’s lower right. C4H8 is, for example, a molecular formula.
  • Empirical: An empirical formula, instead of specifying the atom count, talks in terms of ratios. The subscripts in the formula are reduced to the smallest whole number possible. For example, if C6H12O6 is glucose’s molecular formula, then CH2O would be its empirical formula. Similarly, C5H10O5 is the molecular formula of ribose, and CH2O is the formula’s empirical version.
  • Structural: A structural formula indicates the elements or atoms part of a molecule, their arrangement, and also how different atoms are linked to each other. The formula comprises atom symbols linked by short lines. These lines represent the chemical bond between the atoms. A single line denotes a single bond. Similarly, two and three lines represent double and triple bonds, respectively.
  • Condensed: A condensed formula is basically a type of structural or empirical formula that shows the number of atoms present in a molecule but doesn’t give details about the bonds between the atoms. The formula is usually written in a straight line.

Molecular and empirical are the two commonly used chemical formulas. In fact, a molecular chemical formula is often considered the true formula. It’s easy to write down the empirical formula of a molecule if you know its molecular formula. However, it’s not possible to determine molecular formula from an empirical formula.