Question

Using the periodic table as a guide, determine the number of unpaired electrons for the ground state of Br.

A) 0
B) 1
C) 2
D) 3

Answer 1

The number of unpaired electrons for the ground state of Br is 2 (C).

Step-by-step explanation:

The number of unpaired electrons for the ground state of Br is 2 (C).

Br has 35 electrons, and its electron configuration is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁵. The outermost electron is in the 4p orbital, and there are 5 electrons in that orbital. Since each orbital can hold a maximum of 2 electrons, the first 4 electrons will pair up, and the 5th electron will be unpaired, giving a total of 2 unpaired electrons.