intoduction

2. Intramolecular Forces
 Forces present within molecules between the
atoms
 Comparatively strong forces
 Chemical properties of substance are related to
its intramolecular forces

3. Examples
Covalent bond
 Ionic bond
Coordinate covalent bond

4. Intermolecular Forces

5. Intermolecular Forces
 Set of attractive and repulsive forces
 Present between two molecules
 Weak forces
 Play important role in determining the physical
properties of a substance
 States of substance is determined by these forces

6.  Two or more atoms joined by chemical
bonds form a molecule
 Electrons travel up to the new molecule
 Electrons are concentrated in the most
electronegativity atom area

8. Physical Properties of Intermolecular
forces
 The stronger the intermolecular forces are, the
more energy it will require to pull the
molecules apart
 Molecules that have strong intermolecular
forces also have high melting points and
boiling points

9. Examples
 Dipole-dipole forces
 Dipole-induced dipole forces
 London dispersion forces
 Hydrogen bonding

10. Dipole-dipole forces
 The attractive forces present between oppositely
charged ends of polar molecules are known as
dipole-dipole forces

11. Factors affecting
dipole-dipole forces
(i) Electronegativity difference
 Greater the electronegativity difference,
greater will be dipole-dipole forces

12. (ii) Intermolecular distance
Forces are strong in liquids due to less
distance between molecules
Forces are weak in gaseous phase due to
greater distance between molecules

13. Dipole-induced dipole forces
 The attractive forces present between
permanent dipole and induced dipole are
called dipole-induced dipole forces

14.  A dipole-induced dipole attraction is a weak
attraction

15. London dispersion forces
 The attractive forces between temporary
dipole in one molecule and temporary
induced dipole in an adjacent molecule

16.  The weakest intermolecular force.
 Present between any two molecules
(even polar molecules) when they are almost
touching.

17. Hydrogen bonding
 The force of attraction between
hydrogen atom and electronegative
atom of another molecule

18.  Strongest type of intermolecular forces
 Occurs in molecules with very polar bonds
involving hydrogen
H-F
H-N
H-O
 Strength of hydrogen bond is twenty times less
than that of covalent bond

19. The electronegative atoms responsible
for creating hydrogen bonding are
Fluorine
Oxygen
Nitrogen
Chlorine

20. Essential Requirements For An H-bond Are:-
1. A hydrogen atom attached to a highly
electronegative atom;
2. Unshared pair of electrons on the
electronegative atom.