DP Chemistry (last assessment 2024)
Question 17N.2.sl.TZ0.3
| Date | November 2017 | Marks available | [Maximum mark: 5] | Reference code | 17N.2.sl.TZ0.3 |
| Level | sl | Paper | 2 | Time zone | TZ0 |
| Command term | Deduce, Draw, Predict | Question number | 3 | Adapted from | N/A |
3.
[Maximum mark: 5]
17N.2.sl.TZ0.3
Lewis (electron dot) structures are useful models.
(a)
Draw the Lewis (electron dot) structures of PF3 and PF4+ and use the VSEPR theory to deduce the molecular geometry of each species.
[4]
Markscheme
Accept any combination of dots, crosses and lines.
Ignore missing brackets and positive charge.
Penalize missing lone pairs once only.
Do not apply ECF for molecular geometry.
(b)
Predict with a reason, whether the molecule PF3 is polar or non-polar.
[1]
Markscheme
polar AND bond polarities/dipoles do not cancel out
OR
polar AND unsymmetrical distribution of charge
Apply ECF from part (a) molecular geometry.
