chemistry, Van der Waals, forces, interactions, attraction, with, examples ,

Van der Waals forces


Hello friends, welcome to our blog today we are going to discuss the Van der Waals forces . We know that the constituents of matter are atoms and molecules they have their properties depending upon their size and electronic configuration.


The different states of matter are because of the different in magnitude(strength) of forces exist between them the inter molecular forces are also called as force of interaction.

inter molecular forces

the attractive or repulsive in nature the forces which are present in different atoms are known as inter atomic forces .

Remember
Van der Waals forces do not include the electrostatic forces present in the ionic bond which is made up of cation and anion.

These inter molecular forces are of different type

1. Dipolar forces2. Ion Dipolar forces3. Ion induced dipole interaction and  4. instantaneous dipolar interaction


These are collectively called as Van der Waals forces and award was given to the scientist Johansson Van der Waals. This does not include hydrogen bonding




1. Dipolar forces:-

In this chemical bonding the covalent bond exist between the different atoms participating with their different electronegativity of polar nature. The more electronegative atom has partially negative charge while lesser electronegative atom has partially positive charge.



2. Ion dipole interaction:-

Ion dipole interaction as the name suggests present of ion (cations and anions) and polar molecules . the ion is attracted towards the opposite end of the dipole molecule the strength of the interaction depends upon


1. size of fine the dipole moment and
2. size of Polar molecules


for example:- when salt is dissolved in polar solvent that is sodium chloride soluble in water when we add in water there will be formation of the anion and cation of Na+ and CL- surrounded by the millions of H2O molecules and there is an Ion dipole interaction this is also called as hydration process.


Hydration process :- In which a certain amount of energy is released when there is an attraction due to this interaction there is a solubility of NaCl and other crystalline salt in water.


3.Ion induced dipole interaction:-

In these cases ions induced polarity on non polar molecules when they we approach each other. For example. when nitrate ion and iodine molecule approach each other. negative charge of nitrate Ion induced(create) polarity on the iodine molecule which becomes Di polar. Actually the share pair electrons  not remain at the center it get displaced iodine atoms which acquire  negative charge while other iodine atom has partially positive charge.



please note that dipole interaction can also be present between ion and non polar molecules

4. Instantaneous dipolar interaction

Instantaneous dipole interaction it is also called as London forces. In this molecular solid are closely packed in space if they are polar that bind with dipole dipole interaction however if they are non polar in nature then binding forces or London forces
These forces of attraction are generally weak and their magnitude(strength) depends upon

1. the surface area of contact
2.Molecular size greater the molecular size more the force of attraction

these helps comparing of boiling point for example the isomers . Pentane the straight chain isomers have higher boiling point as compared to branched chain isomers . the branch of the carbon atom changed the molecular size and also their boiling point decreases.


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