DP Chemistry (first assessment 2025)

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Question 19M.1A.SL.TZ1.4

Date	May 2019	Marks available	[Maximum mark: 1]	Reference code	19M.1A.SL.TZ1.4
Level	SL	Paper	1A	Time zone	TZ1
Command term		Question number	4	Adapted from	N/A

4.

[Maximum mark: 1]

19M.1A.SL.TZ1.4

What is the ground state electron configuration of an atom of chromium, Cr (Z = 24)?

A. [Ar]3d⁶

B. [Ar]4s²3d⁴

C. [Ar]4s¹3d⁵

D. [Ar]4s²4p⁴

[1]

Markscheme

C

Examiners report

Some candidates had ground state configuration of Cr as 4s² 3d⁴ rather than 4s¹ 3d⁵

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.