States of Matter

States of matter

We know matter exists in three states Solid,liquid and gas. In this chapter, we will learn more about States of matter from perspective of intermolecular forces, Thermal interaction

Intermolecular Forces

These are the forces of attraction and repulsion between interacting particles (atoms and molecules)
This term does not include the electrostatic forces that exist between the two oppositely charged ions and the forces that hold atoms of a molecule together i.e., covalent bonds


These are attractive inter molecular forces with least intensity.

Dipole – Dipole forces

These are the attractive forces between the dipole/ dipolar molecular which have permanent dipole moment. This interaction is stronger than London forces but weaker than ion – ion forces.
dipole dipole forces

Ion – Dipole Interaction:

This is the force of attraction which exists between ions (anion & cation and polar molecules. Ion is attracted towards oppositely charged end of polar molecule.

Dipole– Induced Dipole forces:

These type of interaction is present between polar molecule and non-polar molecule.  Permanent dipole of the polar molecule induces dipole on the electrically neutral molecule by deforming its electronic cloud. So, an induced dipole is introduced in the other molecule

London Forces/ Dispersion forces

These forces exist in non – polar molecules. As such polar molecules are electrically symmetrical but at some time dipole could be induced momentarily due to distortion of the electron cloud. The induced dipole introduced dipole in close by molecules also, the force of attraction between these induced dipoles is called dispersion forces or London forces
symmetrical distribution of electron charge cloud
The above figure shows the symmetrical distribution of electron charge cloud
induced dipole and dispersion forces
The above figures show the induced dipole and dispersion forces

Hydrogen Bonds

This is special case of dipole-dipole interaction. It is found in the molecules in which highly polar N–H, O–H or H–F bonds are present. The positively charged Hydrogen atom is attracted towards the negatively charge atom, So, molecules are linked together with these forces of attraction
hydrogen bond forces

Thermal Energy

It is the measure of the average kinetic energy of the particles of the matter and it is responsible for movement of the particle. This movement is called thermal motion

Intermolecular Forces and Thermal interaction

Intermolecular forces tries to bind the particles while thermal motion is about movement.The three states of matter are the result of balanced between the Intermolecular Forces and Thermal interaction
Intermolcular Forces and Thermal interaction

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