Chapter 5, Problem

Interpretation Introduction

Interpretation: The correct electron configuration for silicon, atomic number 14 needs to be selected.

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

The correct option is (D).

Explanation of Solution

Reason for correct option:

The given element is silicon. The atomic number of silicon is 14; thus, there are 14 electrons in a silicon 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:

  $1s^{2}2s^{2}2p^{6}3s^{2}3p^2$

Therefore, option (D) is correct.

Conclusion

Reason for incorrect options:

The electronic configuration given in option (A) is as follows:

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

Since the maximum number of electrons hold by p and d orbitals are 6 and 10 respectively also, first, lower energy sublevels are filled then the filling of a new sublevel takes place, $2p^2$ is not a correct configuration. Here, $2p^2$ sublevel must have 6 electrons.

The electronic configuration given in option (B) is as follows:

  $1s^{2}2s^{2}2p^{4}3s^{2}3p^4$

Here, $2p$ and 3p sublevels are not filled correctly. The maximum number of electrons a p sublevel can hold is 6. Thus, the above configuration is incorrect.

The electronic configuration given in option (C) is as follows:

  $1s^{2}2s^{6}2p^6$

Here, 2s orbital is filled incorrectly. The maximum number of electrons s sublevel can hold is 2. Thus, it cannot have 6 electrons and the above configuration is incorrect.

Therefore, options (A), (B), and (C) are incorrect.