Chapter 1, Problem 1E.2BST

Interpretation Introduction

Interpretation:

The ground state configuration of arsenic atom has to be predicted.

Concept introduction:

Electronic configuration: The electron configuration is the distribution of electrons of an atom or molecule in atomic or molecular orbitals.

Electrons occupy the lowest energy orbitals. The increasing order of orbital energy is $s,p,dandf.$  The lowest energy orbital is $ls.$

The energy order of the orbital for the first three periods is as follows,

    $ls,2s,2p,3s,and3p.$

The orbital which is closer to the nucleus has lower energy; therefore the $2s$ is lower in energy than $3s.$   Accordingly $2s$ is lower in energy than $2pand4s$ is lower in energy than $3d.$

In general, the orbitals can hold maximum of two electrons, the two electrons must have opposite spin.

The subshell ordering by Aufbau principle is given below,

    $ls,2s,2p,3s,3p,4s,3d,4p,5s,4d,5p,6s,4f,5d,6p,7s,5f,6d,7p,8s,\mathrm{...}$