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UPSC Combined Geo-Scientist

Chemist

  • 3 descriptive papers
  • 200 marks each
  • 3 h per paper

Mains Paper I covers inorganic chemistry.

UPSC Combined Geo-Scientist, Mains · 2023 · Mains Paper I

Q10(a). Atomic radii across the 3d series

Question

Why does atomic radii of transition metals first decrease, remain constant and then increase as one moves from left to right along the 3d series?

Answer in brief

Increasing nuclear charge causes the initial contraction; increasing d-electron shielding and repulsion flatten the trend, while changes in late-series bonding permit a small increase.

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Topic notes: transition elements: 3d, 4d and 5d compared, atomic radii and the lanthanide contraction, oxidation states and oxidising power, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversatomic radii 3d seriestransition metal trendsshielding effecteffective nuclear charge

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