What Is the Difference Between a Molecule and a Compound?

They have similarities too

This is the three-dimensional structure for ozone, which consists of three oxygen atoms bonded together. Ozone is a molecule, but not a compound.
This is the three-dimensional structure for ozone, which consists of three oxygen atoms bonded together. Ozone is a molecule, but not a compound. INDIGO MOLECULAR IMAGES / Getty Images

A compound is a type of molecule. A molecule is formed when two or more atoms of an element chemically join together. If the types of atoms are different from each other, a compound is formed. Not all molecules are compounds, because some molecules, such as hydrogen gas or ozone, consist only of one element or type of atom.

Molecule Examples

Some examples of molecules include:

  • Water: H2O
  • Oxygen: O2
  • Ozone: O3

Compound Examples

Some examples of compounds include:

  • Salt: NaCl
  • Water: H2O