DP Chemistry (first assessment 2025)
Question 22M.2.SL.TZ1.1e(iii)
| Date | May 2022 | Marks available | [Maximum mark: 1] | Reference code | 22M.2.SL.TZ1.1e(iii) |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Determine, Justify | Question number | e(iii) | Adapted from | N/A |
e(iii).
[Maximum mark: 1]
22M.2.SL.TZ1.1e(iii)
(e(iii))
The nitride ion and the magnesium ion are isoelectronic (they have the same electron configuration). Determine, giving a reason, which has the greater ionic radius.
[1]
Markscheme
nitride AND smaller nuclear charge/number of protons/atomic number ✔
Examiners report
In spite of being given the meaning of "isoelectronic", many candidates talked about the differing number of electrons and only about 30% could correctly analyse the situation in terms of nuclear charge.
Syllabus sections
Structure 2. Models of bonding and structure » Structure 2.1—The ionic model » Structure 2.1.1—When metal atoms lose electrons, they form positive ions called cations. When non-metal atoms gain electrons, they form negative ions called anions. Predict the charge of an ion from the electron configuration of the atom.
Structure 1. Models of the particulate nature of matter » Structure 1.3—Electron configurations » Structure 1.3.5—Each orbital has a defined energy state for a given electron configuration and chemical environment, and can hold two electrons of opposite spin. Sublevels contain a fixed number of orbitals, regions of space where there is a high probability of finding an electron. Apply the Aufbau principle, Hund’s rule and the Pauli exclusion principle to deduce electron configurations for atoms and ions up to Z = 36.