How Atoms and Molecules Move in Liquid

Would you say that a glass of water has energy? You would be correct if you answered 'yes', and even more correct if you added 'there are three types of energy in a the glass of water', although you can't see or feel any of the energy in the glass. This hidden energy is called internal energy. The three types of internal energy in liquids are:

• Translational kinetic energy – linear motion of the atoms or molecules

• Vibrational and rotational kinetic energy – movement by the bonds within a molecule, and by the turning about of the molecule on its axis

• Intermolecular forces potential energy – stored energy that arises from attractions between atoms or molecules

Kinetic energy is the energy of motion, and potential energy is stored energy. 

So even though you may not be able to see or feel these energies, the microscopic world of liquids is very active!

The liquid state of matter is intermediate between the gas state and the solid state, so let's look at liquids by comparing them to gases and to solids: