How would you account for the following?
i) Actinoid contraction is greater than lanthanoid contraction.
ii) Transition metals form coloured compounds.
i) Actinoid contraction is greater than lanthanoid contraction.
ii) Transition metals form coloured compounds.
Solution
(i) The 5f orbitals are more diffuse and shield the nuclear charge even less effectively than 4f orbitals do. Each successive actinoid therefore feels a larger jump in effective nuclear charge, and the size decrease from element to element (actinoid contraction) is greater than in the lanthanoids.
(ii) Transition-metal ions possess incompletely filled d-orbitals, split by the surrounding ligands. Electrons absorb specific visible wavelengths to jump within the split set (d–d transitions); the complementary transmitted light is the colour we see.
(ii) Transition-metal ions possess incompletely filled d-orbitals, split by the surrounding ligands. Electrons absorb specific visible wavelengths to jump within the split set (d–d transitions); the complementary transmitted light is the colour we see.
CBSE Class 12 Board · 2015 · Delhi · Subjective