Chapter 8, Problem 1KSP

Which of the following atoms must always obey the octet rule? (Select all that apply.)

(a)

C

(b)

N

(c)

S

(d)

Br

(e)

Xe

Interpretation Introduction

Interpretation:

The following atom(s)thatalways obeys the octet rule is to be determined.

Concept introduction:

The octet rule states that every element in the main group should have eight electrons in its valence shell in order to attain a noble gas configuration.

Valence electrons are the electrons that are present in theoutermost shell of an element.

Answer to Problem 1KSP

Solution: Options (a), (b), and (e).

Explanation of Solution

Reason for the correct option:

Since carbon and nitrogen are smaller in size and do not have a vacant d-orbital, they have to follow the octet rule to form stable compounds.

Xenon belongs to the noble gas or the eighteenth group. So, it already has eight electrons in thevalence shell. So, it also follows the octet rule.

Thus, the elements $\text{C,}\text{N, and Xe}$ always obey the octet rule.

Hence, options (a), (b), and (e) are correct.

Reason for the incorrect options:

Option (c) is incorrect because sulphur is bigger in size and has a vacant d-orbital. Therefore, it can form stable compounds without following the octet rule.

Option (d) is incorrect because bromine is bigger in size and has a vacant d-orbital. Therefore, it can form stable compounds without following the octet rule.

Hence, options(c) and(d) are incorrect.