Chapter 4, Problem 13STP

Interpretation Introduction

Interpretation:

Average atomic mass of neon is to be calculated using the table of isotopes.

Concept introduction:

Isotope is the same number of protons and electrons but has a different number of neutrons in an atom of the same element. The average atomic mass is the sum of the masses the isotopes multiplied their respective percentage of natural abundance.

Answer to Problem 13STP

Average atomic mass of neon $=20.10amu$

Explanation of Solution

Given information:

Characteristics of naturally occurring neon isotopes:

Isotope	Atomic Number	Mass (amu)	Percent Abundance
$Ne$	10	$19.992$	$90.48$
$Ne$	10	$20.994$	$0.27$
$Ne$	10	$21.991$	$9.25$

To calculate the average atomic mass of neon, use the following formula:

$Averageatomicmass=f_1{M}_1+f_2{M}_2+f_3{M}_3+\mathrm{...}+f_n{M}_n$

Where f is natural abundance of the isotope and M is weight of the isotope.

Thus, the average atomic mass of neon $=19.92\times 0.9092+20.99\times 0.0025+21.99\times 0.0883=20.10amu$

Conclusion

Hence, $20.10amu$ is the average atomic mass of neon.