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Explain the anomalous behaviour of chromium.

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Question

Explain the anomalous behaviour of chromium.

Explain
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Solution

  1. Chromium (Cr) has atomic number 24.
  2. Its expected electronic configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d4.
  3. The 3d orbital is less stable, as it is not half-filled.
  4. Due to inter-electronic repulsion forces, one 4s electron enters into the 3d orbital. This makes the 4s and 3d orbitals half-filled, which gives extra stability, and the electronic configuration of Cr becomes 1s2 2s2 2p6 3s2 3p6 4s1 3d5.
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Chapter 4: Structure of Atom - Exercises [Page 54]

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Balbharati Chemistry [English] Standard 11 Maharashtra State Board
Chapter 4 Structure of Atom
Exercises | Q 6. (I) | Page 54

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