intermolecular forces

Question 1

What are the types of intermolecular forces

Answer 1

-Van der Waals forces
-Permanent dipole-dipole forces
-Hydrogen forces

Question 2

what is a dipole

Answer 2

-The presence of a dipole means that the molecule has a partially positive end and a partially negative end.

Question 3

Details of Van der Waals forces

Answer 3

-These are present in all molecular substances.

-They occur because the electrons are constantly moving around and there will be an uneven electron distribution at any given moment in time.
This causes a temporary dipole within a molecule.

-This temporary dipole induces a temporary dipole in a neighbouring molecule. There is then an attraction between these molecules - this is a temporary induced dipole-dipole attraction.

Question 4

What affects the Van der Waals forces

Answer 4

-The bigger the molecule (the more electrons) the greater the Van der Waals force

Question 5

What is the order of strength of intermolecular forces

Answer 5

-Hydrogen bonding >dipole-dipole>Van der Waals

Question 6

Details of permanent dipole-dipole

Answer 6

-Permanent dipole-dipole attraction between POLAR molecules (eg HCl)

Question 7

Details of hydrogen bonding

Answer 7

-H atom bonded to a very electronegative atom : F,O,N

-The polar bond between the H and N/O/F leaves the H nucleus exposed as H only has one electron.

-Therefore there is a strong attraction from the lone pair on the N/O/F of one molecule to the exposed H nucleus of another molecule.

Question 8

what are example of H bonding

Answer 8

H2O, NH3, alcohols, carboxylic acids, amines,amino acids.

Question 9

how to tell if a molecule is polar

Answer 9

-There are different terminal atoms
or
-Lone pairs arose central atom