Chapter 5.2, Problem 14LC

Interpretation Introduction

Interpretation: The electronic configuration of an arsenic atom needs to be determined.

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 14LC

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

Explanation of Solution

The atomic number of the element arsenic is 33. Since the atomic number is equal to the number of electrons in an atom, thus, the number of electrons present in an arsenic atom is 33. The electron configuration explains the distribution of the total number of electrons in atomic orbitals. Here, the s orbital can maximum have 2 electrons, the p orbital can have 6 and the d orbital can have a maximum of 10 electrons.

The distribution of electrons can be represented as follows:

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

Here, 4s orbital is filled before 3d . Thus, the electronic configuration of the arsenic atom is as follows:

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

Conclusion

Therefore, the electronic configuration of the arsenic atom is as follows:

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