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The d- and f-Block Elements
Electronic Configuration and Ionisation Enthalpy of f-block Elements
1 question from 1 paper, each with its answer.
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- of The d- and f-Block Elements
- 1.32%
Concepts tested
- stability of half-filled 4f subshell in Gd
All Questions
2022 1 question
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Gadolinium has a low value of third ionisation enthalpy because of$_{64}Gd = [Xe]\,4f^7 5d^1 6s^2$; $Gd^{2+} = [Xe]\,4f^7 5d^1$ The third electron is removed from 5d, leaving the stable half-filled $4f^7$ configuration, which has maximum exchange energy. So Gd has a low third ionisation enthalpy because of high exchange enthalpy.