Question

1. determine the average atomic mass of the isotopes in the data table below. show work: atomic mass (u) natural abundance (%) work: 10.01 19.9 11.01 80.1

Explanation:

Step1: Convert percentages to decimals

$19.9\%=0.199$, $80.1\% = 0.801$

Step2: Calculate weighted - sum

The formula for average atomic mass $A$ is $A=\sum_{i}m_i\times a_i$, where $m_i$ is the atomic mass of the isotope and $a_i$ is its natural abundance.
$A=(10.01\times0.199)+(11.01\times0.801)$
$A = 10.01\times0.199+11.01\times0.801=1.99199 + 8.81901$
$A=10.811$

Answer:

$10.811$