intermolecular forces

Question 1

what is a permanent dipole?

Answer 1

when a bond is polar, the more electronegative atom pulls the electron pair towards it, creating a negative dipole on it and forming a positive dipole on the less electronegative atom.

Question 2

what is a permanent dipole-dipole interaction?

Answer 2

the electrostatic attraction between oppositely charged permanent dipoles of neighbouring molecules in polar bonds only.
eg. H-Cl——-H-Cl

Question 3

what is the problem of permanent dipole-dipole interactions?

Answer 3

the dipoles are not always aligned to produce an attraction because of the random movements of molecules.

Question 4

what does the strength of PDD forces increase with?

Answer 4

• more electrons => inc for molecules with higher Mr
• more contact surface area => larger-elongated
• stronger IMF = higher BP

Question 5

what is a temporary dipole?

Answer 5

as electrons are constantly moving around the nucleus, there will be an uneven distribution of electrons resulting in one half of the molecule more negatively charged than the other

Question 6

what is an induced dipole?

Answer 6

when electron distribution around a molecule is influenced by a charged particle

Question 7

what is an induced-dipole induced-dipole interaction?

Answer 7

when a temporary dipoles induce temporary dipoles into a neighbouring molecule as it pulls the neighbouring electron cloud towards it. it is the weakest force as the temp and IDID forces are small

Question 8

what is a hydrogen bond?

Answer 8

an electrostatic attraction between hydrogen and a very electronegative element (nitrogen, oxygen or fluorine). it is the strongest force

Question 9

wh