Chemical Formulas

You use a number of chemical substances in your daily life e.g. chemicals to clean houses, to wash clothes, to disinfect things, to kill insects and so on. Now what are the chemicals?  Chemicals are the substances that are made up of atoms arranged in particular order and in a fixed proportion. A chemical formula tells you about those atoms, their proportion and their arrangements in the chemical substance.

Each chemical compound is different and has different atoms with different proportions. So obviously there is a different chemical formula for each substance.

What is the chemical formula?

chemical formula describes number of atoms present in an element of a  chemical compound. A chemical compound forms with the combination of two elements. Each. Chemical formula not only tells the numbers of atoms but also contains their symbols.


“A chemical formula is the symbolic and numerical representation of atoms present in a molecule”

Kinds of chemical Formula

There are three different types of chemical formulae i.e. empirical formula, molecular formula and structural formula. Each kind of the formula provides different information of a particular chemical compound. Let’s discuss each of three different types in detail!

Empirical formula

It is the simple representation of the relative number of atoms present in the compound The word empirical means something that is proved by observation. In chemistry, empirical formula is defined as the simplest whole number ratio of elements that form a chemical compound. E.g. empirical formula of water is H2O. While formula of Hydrogen peroxide and Di sulfur oxide is HO and SO respectively.   This kind of chemical formula comes from the experimental data that is why it is known as empirical formula.

Molecular Formula

The molecular formula is also known as the true formula of a chemical compound. It represents the actual or true number of elements present in a molecule of the compound. In other words, a molecular formula tells the number of atoms present in one molecule of a substance. The molecular formula of Di Sulfur Oxide is S2O2 , Hydrogen per Oxide has the molecular formula H2O2 .  The formula uses symbols to represent the kind of atoms while subscript numbers to describe the number of atom.

Structural Formula

The structural formula of a chemical compound shows the arrangement of atoms in the molecule of that compound. Structural formulae represent the structure and arrangement of the atoms to form bonds to form molecule in a chemical compound. A structural formula has symbol to represent the atom while short lines depict chemical bonds i.e. one line represents a single bond, two line show a double bond and three line represent a triple bond.

Chemical Formula Examples

You can understand the topic with the help of chemical formula examples. With the help of these examples, you can understand how to write a chemical formula

Before writing the formula of a compound, you should know the formula of the radicals the symbol of the element/ radical, and the valency of the radicals/ elements present in it. Follow the given instructions to write the formula of any chemical substance.

  1. First, Write the symbols of all the elements  present in the compound.
  2. Now Write valency below the symbol of each element
  3. Intersect the valency’s of the elements.
  4. Write the valency of second atom as subscript of first one.
  5.  Now write valency of first atom as subscript of second.

Remember! Most of the compounds are binary in nature which means that they contain two elements. However, some compounds also have  more than two elements. A compound can be a combination of a metal and non metal. So writing the formula, keep t metal first and then write non metal. For example, in KCl (potassium Chloride) contains K+ (metal ion).

Chemical formula Book

if you want to know the chemical formula of any chemical compound and you don’t know  where to find it? The answer is if you know the substance, formula of the substance and other relevant information is usually present in a handbook usually called Chemical formula book.  In this type of book, the chemical formulas are listed in the form of tables making you easy to find the required formula. If you want to make any chemical, it’s necessary that you should the formula of that chemical.

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