Intermolecular Bonds

Question 1

Explain instantaneous dipole - induced dipole bonds

Answer 1

1) electrons in charge clouds always moving - at a particular moment electrons likely to be more on 1 side = instantaneous dipole (ID)
2) this D induces another ID in opp. direction of neighbouring atom = D’s attracted
3) new dipole induces a 3rd = domino effect
4) electrons moving = dipoles always created + destroyed -> overall atoms attracted

Question 2

How does the shape of organic molecules effect the strength of their IM bonds?

Answer 2

Longer = stronger - more molecular surface contact + more electrons to interact
= more energy to overcome instantaneous dipole - induced dipole bonds

Branched = can’t pack closely -> small molecular surface contact
= fewer instantaneous dipole - induced dipole bonds can form

Question 3

The heavier the atom/molecule…

Answer 3

the stronger the intermolecular bonds

Question 4

ALL atoms + molecules form…

Answer 4

Instantaneous dipole - induced dipole bonds

Question 5

Trend on boiling points of the halogens?

Answer 5

As you go DOWN the group:
the instantaneous dipole-induced dipole bonds increase (+BP) because molecular WEIGHT INCREASES –> no. shells increases –> atomic size increases

Question 6

Polar molecules have…

Answer 6

permanent dipole-permanent dipole bonds

δ+ and δ- charges on polar molecules = weak electrostatic forces of attraction between molecules = PD-PD bonds

They happen AS WELL AS instantaneous-induced bonds

Question 7

Why does water bend if put next to an electrostatic ally charged rod?

Answer 7

Water = polar –> contains permanent dipoles
Polar molecules in liquid can turn around so opp. charged end attracted towards the rod

(Doesn’t matter if rod +/- charge)

Question 8

What’s the strongest type of intermolecular bond?

Answer 8

Hydrogen bonding