A molecule is a particle containing two or more atoms. If it contains only one type of atom it is called an element. An exception to this is diatomic gases (for example: Oxygen, O2, where the molecule contains two atoms of the same element, bonded covalently. If it contains two or more different types of element which are bonded it is called a compound.
Diatomic molecules are molecules which are made up of only two atoms, of either the same or different elements. Examples:
- Oxygen, O2
- Carbon Monoxide CO
- all the halogens.