Chapter 5.2, Problem 13LC

Interpretation Introduction

Interpretation: The reason for one electron in a potassium atom to go to the fourth energy level but not to the third energy level where 8 electrons are already there.

Concept introduction: The electron configuration explains the electron distribution in atomic orbitals. There is a standard notation to write an electron configuration. The atomic shell is written in a sequence with the number of electrons in superscript.

Answer to Problem 13LC

Due to complete octet.

Explanation of Solution

The atomic number of potassium is 19. The electronic configuration can be represented as follows:

  $1s^{2}2s^{2}2p^{6}3s^1$

Here, one electron is in the 3s sublevel because there are already 8 electrons in the third energy level.

For any sublevel, there is a maximum number of electrons possible. An s orbital can maximum hold 2 electrons and a p orbital can maximum hold 6 electrons. Since there is a maximum number of electrons already there in the 2s and 2p orbitals, thus, a new electron goes into the fourth energy level that is 3s .

Conclusion

The third level has a complete octet, thus, the next electron goes into the fourth energy level.