Question 19M.2.hl.TZ2.3c
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.hl.TZ2.3c |
| Level | hl | Paper | 2 | Time zone | TZ2 |
| Command term | Explain | Question number | c | Adapted from | N/A |
Dinitrogen monoxide, N2O, causes depletion of ozone in the stratosphere.
Explain why the first ionization energy of nitrogen is greater than both carbon and oxygen.
Nitrogen and carbon:
Nitrogen and oxygen:
[2]
Nitrogen and carbon:
N has greater nuclear charge/«one» more proton «and electrons both lost from singly filled p-orbitals» [✔]
Nitrogen and oxygen:
O has a doubly filled «p-»orbital
OR
N has only singly occupied «p-»orbitals [✔]
Note: Accept “greater e– - e- repulsion in O” or “lower e– - e- repulsion in N”.
Accept box annotation of electrons for M2.
Mixed responses here; the explanation of higher IE for N with respect to C was less well explained, though it should have been the easiest. It was good to see that most candidates could explain the difference in IE of N and O, either mentioning paired/unpaired electrons or drawing box diagrams.
