Question

neon has three stable naturally occurring isotopes. the isotopic mass and percent abundance of these isotopes are given in the table.

isotope	isotopic mass (u)	abundance (%)
$^{21}$ne	20.99	0.27
$^{22}$ne	21.99	9.25

calculate the average atomic mass of neon.

Explanation:

Step1: Convert percentages to decimals

For \(^{20}\text{Ne}\): \(90.48\% = \frac{90.48}{100}=0.9048\)
For \(^{21}\text{Ne}\): \(0.27\%=\frac{0.27}{100} = 0.0027\)
For \(^{22}\text{Ne}\): \(9.25\%=\frac{9.25}{100}=0.0925\)

Step2: Multiply each isotopic mass by its decimal abundance

For \(^{20}\text{Ne}\): \(19.99\times0.9048 = 19.99\times0.9048\approx18.09\)
For \(^{21}\text{Ne}\): \(20.99\times0.0027=20.99\times0.0027\approx0.0567\)
For \(^{22}\text{Ne}\): \(21.99\times0.0925 = 21.99\times0.0925\approx2.034\)

Step3: Sum the products

Average atomic mass \(= 18.09 + 0.0567+2.034\approx20.18\) (u)

Answer:

The average atomic mass of neon is approximately \(\boldsymbol{20.18}\) u.