Question

The number of d-electrons in $F{e}^{2+}(Z=26)$ is not equal to the number of electrons in which one of the following?

• A. d-electrons in Fe (Z=26)
• B. p-electrons in Ne (Z=10)
• C. s-electrons in Mg (Z=12)
• D. p-electrons in Cl (Z=17)

Answer 1

Answer: (D)

Electronic configuration of the elements are:
$F{e}^{2+}:1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^6$
number of d-electrons $=6$ $F{e}^{2+}:1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^6$ -has 6 electrons in d-orbital i.e. same as in $d-$ robital of $F{e}^{2+}$
$Ne:1s^{2}2s^{2}2p^6$ -has 6 electrons in p-orbital i.e. same as in d- robital of $F{e}^{2+}$
$Mg:1s^{2}2s^{2}2p^{6}3s^2$ -has $(2+2+2)6$ electrons in s-orbital i.e. same as in $d-$ robital of $F{e}^{2+}$
$Cl:1s^{2}2s^{2}2p^{6}3s^{2}3p^5$ -has (6+5) 11 electrons in p-orbital and are not same as in d- robital of
$F{e}^{2+}$