9.2 Electronic Configuration of actinoids

  d and f Block Elements

• On the basis of spectral data is clear that the electronic configurations of these elements are not definite.

• The valence shell electronic configuration of these elements is $5{f^{1 - 14}}6{d^{0 - 1}}7{s^2}$.

• Electronic configuration of nearest noble gas element $${}_{86}[Rn] 1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^2}3{d^{10}}4{p^6}4{d^{10}}4{f^{14}}5{s^2}5{p^6}5{d^{10}}6{s^2} 6{p^6}$$

• Electronic configuration of $Ac$ $(89)$ is $[Rn] -$ $5{d^0}6{d^1}7{s^2}$. It does not contain any $f$ electrons due to empty stability of $5f$.