Complete Electron Configuration (No Arrows) for Chromium, Antimony, and Calcium

Write the complete electron configuration (no arrows) for Chromium, Antimony, and Calcium.

Subject: General Chemistry Chapter: Electrons in Atoms Topic: Electron Configuration Answer included

Written by STEM Calculators Published February 27, 2026 Updated February 27, 2026

Write the complete electron configuration (no arrows) for Chromium Antimony Calcium complete electron configuration electron configuration chromium electron configuration Cr electron configuration antimony electron configuration Sb electron configuration calcium electron configuration

Accepted answer Answer included

Write the complete electron configuration (no arrows) for Chromium, Antimony, and Calcium. Complete configurations list every occupied subshell in the correct filling order with superscript electron counts.

Subshell order and notation

Electron configuration in general chemistry follows the Aufbau filling order across subshells (s, p, d) together with the Pauli exclusion principle (maximum 2 electrons per orbital) and Hund’s rule (maximizing unpaired electrons in degenerate orbitals). Complete electron configuration (no arrows) uses subshell labels such as 3p and 3d with superscripts for electron counts.

The segmented bar shows the subshell sequence up through 5p. Calcium ends exactly at 4s² (20). Chromium lies early in the 3d region (24) and exhibits the well-known 4s¹ 3d⁵ exception. Antimony lies within 5p (51), corresponding to 5p³.

Complete electron configurations (no arrows)

Calcium (Ca), \(Z=20\): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

Chromium (Cr), \(Z=24\): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵

Antimony (Sb), \(Z=51\): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p³

Chromium exception note

Chromium is a standard transition-metal exception to the simple Aufbau expectation. The ground-state electron configuration is written with a half-filled d subshell: 4s¹ 3d⁵ rather than 4s² 3d⁴.

Electron-count checks

The superscripts sum to the atomic number for each neutral atom:

\[ \text{Ca: } 2+2+6+2+6+2 = 20 \] \[ \text{Cr: } 2+2+6+2+6+1+5 = 24 \] \[ \text{Sb: } 2+2+6+2+6+2+10+6+2+10+3 = 51 \]

Summary table

Element	Atomic number \(Z\)	Complete electron configuration (no arrows)	Shorthand (for reference)
Calcium (Ca)	20	1s² 2s² 2p⁶ 3s² 3p⁶ 4s²	[Ar] 4s²
Chromium (Cr)	24	1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵	[Ar] 4s¹ 3d⁵
Antimony (Sb)	51	1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p³	[Kr] 5s² 4d¹⁰ 5p³

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Subshell order and notation

Complete electron configurations (no arrows)

Chromium exception note

Electron-count checks

Summary table

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