DP Chemistry (first assessment 2025)

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Question 21M.2.SL.TZ2.2b(i)

Date	May 2021	Marks available	[Maximum mark: 2]	Reference code	21M.2.SL.TZ2.2b(i)
Level	SL	Paper	2	Time zone	TZ2
Command term	State	Question number	b(i)	Adapted from	N/A

b(i).

[Maximum mark: 2]

21M.2.SL.TZ2.2b(i)

(b(i))

State the condensed electron configurations for Cr and Cr3⁺.

[2]

Markscheme

Cr:
[Ar] 4s¹3d⁵ ✓

Cr³⁺:
[Ar] 3d³ ✓

Accept “[Ar] 3d⁵4s¹”.

Accept “[Ar] 3d³4s⁰”.

Award [1 max] for two correct full electron configurations “1s²2s²2p⁶3s²3p⁶4s¹3d⁵ AND 1s²2s²2p⁶3s²3p⁶3d³”.

Award [1 max] for 4s¹3d⁵ AND 3d³.

Syllabus sections

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.