Van der Waals Interactions

Hello everyone,

Today I will be explaining about Ven der Waals Interaction

Van der Waals  interaction, named after Dutch scientist Johannes Diderik van der Waals, is the sum of the attractive or repulsive forces between molecules (or between parts of the same molecule) other than those due to covalent bonds, or the electrostatic interaction of ions with one another, with neutral molecules, or with charged molecules. The resulting Van der Waals forces can be attractive or repulsive

Van der Waals forces are driven by induced electrical interactions between two or more atoms or molecules that are very close to each other. Van der Waals interaction is the weakest of all intermolecular attractions between molecules. However, with a lot of Van der Waals forces interacting between two objects, the interaction can be very strong.

• The main characteristics of van der Waals forces are:- 
• They are weaker than normal covalent ionic bonds.
• Van der Waals forces are additive and cannot be saturated.
• They have no directional characteristic.
• They are all short - range forces and hence only interactions between nearest need to be considered instead of all the particles. The greater is the attraction if the molecules are closer due to Van der Waals forces.
• Van der Waals forces are independent of temperature except dipole - dipole interactions.

The important aspects of Quantum Mechanics strongly suggest that the electrons are constantly are moving in an atom, so dipoles are probable of occurring. A dipole is defined as molecules or atoms with equal and opposite electrical charges separated by a small distance.This is how instantaneous dipoles occur. When groups of electrons move to one end of the atom, it creates a dipole.

It is probable to find the electrons in this state:

Dipole-Dipole interactions occur between molecules that have permanent dipoles; these molecules are also referred to as polar molecules. The figure below shows the electrostatic interaction between two dipoles.

When two Uncharged atoms are brought very close together, their surrounding electron influence each other . Dipole formation take place in nearby atom. the two dipoles weakly attract each other , bringing two atom closer forming a weak Van der waals interactions. As they come closer repulsion occurs. the point at where Van der Waal's attraction exactly balances this repulsive force, the atoms are said to be in Van der Waal's contact.

Hope you like 

with love

-Dixy