Chapter 5, Problem 9STP

Interpretation Introduction

Interpretation: The configuration of the highest occupied energy level for the krypton element needs to be identified.

Concept Introduction: The electronic configuration represents the arrangement of electrons in atomic orbitals. Here, s , p , d, and f are sublevels in which electrons are distributed. The maximum number of electrons in s , p , d, and f orbitals are 2, 6, 10, and 14.

Answer to Problem 9STP

The correct option is (A).

Explanation of Solution

Reason for correct option:

The given element is krypton. The atomic number of krypton is 36 thus, there are 36 electrons in a krypton atom. The increasing order of energy of sublevels is as follows:

  $s<p<d<f$

Thus, the filling of electrons takes place in the order s , p , d, and f .

The electronic configuration can be represented as follows:

  $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^6$

This can be rewritten as follows:

  $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^6$

Thus, the highest occupied energy level is $4s^{2}4p^6$

Therefore, option (A) is correct.

Conclusion

Reason for incorrect options:

The electronic configuration of krypton is as follows:

  $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^6$

The increasing order of energy with respect to principal quantum number is as follows:

  $1<2<3<4$

Thus, the highest occupied energy level will be with principal quantum number 4. From the electronic configuration, there are two sublevels with this principal quantum number that is $s^2{p}^6$ .

Therefore, options (B), (C), (D) and (E) are incorrect options.