Asked in Premeth MDCAT 2025 — Work and Energy, Atomic Structure, Nouns 2025

Sodium-11 has an electronic configuration

Correct answer: B. [Ne] 3s1

  • A. [He]2s1
  • B. [Ne] 3s1
  • C. [Ne]3s2
  • D. [He]2s2

Explanation

The correct electronic configuration for sodium-11 is [Ne] 3s1. Sodium has 11 electrons, and its configuration follows that of the noble gas neon (1s2 2s2 2p6) before adding one electron to the 3s orbital. The other options are incorrect as they represent the configurations of either different elements or incomplete configurations.

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About Electronic Configuration

Electronic configuration describes how electrons occupy shells, subshells and orbitals around an atom. Questions use the Aufbau principle, Pauli exclusion principle and Hund's rule to write configurations, identify valence electrons, form ions and explain periodic trends, including common exceptions such as chromium and copper.

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