intermolecular forces

Question 1

define intermolecular forces

Answer 1

forces between molecules

Question 2

what are the three types of intermoleculer forces?

Answer 2

1. van der waals forces
2. permanent dipole-dipole forces
3. hydrogen bonding

Question 3

how are VDW formed?

Answer 3

electrons are constantly moving around = at nay moment - electrons in the atom are unevenly distributed = the atom has a temporary dipole, which induces another TD in neighbouring molecules

Question 4

what do VDW do for molecules. give an example

Answer 4

they hold the molecule in a lattice arrangement
-> iodine = the molecules are held together in a molecular lattice by weak vdwf - the atoms are held together by covalent bonds

Question 5

what two factors affect the strength of VDWF?

Answer 5

molecular size and points of contact

Question 6

permanent dipole forces

Answer 6

• difference in electronegativity between the charges = forms these forces

Question 7

what is hydrogen bonding?

Answer 7

it’s the strongest intermolecular force and only occurs if hydrogen is covalently bonded to fluorine, oxygen and nitrogen

Question 8

why do bonds become polarised in hydrogen bonding

Answer 8

because F,N AND O are very electronegative -they raw the bonding electrons away from the hydrogen atom, so it becomes more positively charged = increasing the difference in electronegatively