States of Matter – Notes
Intermolecular forces are attractive and repulsive forces between the interacting atoms and molecules.
The force of attraction between the two temporary dipoles is known as dispersion force or London force.
Dipole –Dipole forces are attractive forces that act between the polar molecules with permanent dipole.
The Dipole –Dipole forces are stronger compared to the other London forces.
Dipole-Induced Dipole attractive forces operate when a polar molecule with permanent dipole induces a dipole in a non-polar atom or molecule by deforming its electron cloud.
A special case of Dipole – Dipole interaction called hydrogen bond exists in the molecules with highly polar N-H, O-H or H-F bonds.
The energy of a body arising from the translational, rotational and vibrational motion of its atoms or molecules is called the thermal energy.
The balance between the intermolecular forces and the thermal energy of the molecules is responsible for the physical state of matter.
The physical state of matter depends on the strength of intermolecular bonds and the thermal energy of the particles involved.