How are molecules formed?

Definition of a molecule:

1. A group of atoms bonded together that represents a unit of the chemical compound is known as a molecule.
2. A molecule gives the exact number of atoms of all the elements in a unit of substance.

Formation of a molecule:

1. A molecule is formed when two or more atoms join together i.e. bonds are formed between the atoms.
2. While joining together, each atom shares one electron in bond formation.
3. Thus, a covalent bond results in the formation of a molecule.

Example:

1. When two hydrogen atoms $\mathbf{\left(}\mathbf{H}\mathbf{\right)}$ and one oxygen atom $\mathbf{\left(}\mathbf{O}\mathbf{\right)}$ join together, Water molecule $\mathbf{\left(}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{\right)}$ is formed.