Question

1. calculate the average atomic mass (decimal form)

mass spectrum of silicon

Explanation:

Step1: Recall average - atomic - mass formula

The average atomic mass ($A_{avg}$) of an element with isotopes of masses $m_i$ and abundances $x_i$ is given by $A_{avg}=\sum_{i}m_ix_i$.

Step2: Identify values from the spectrum

For silicon, we have three isotopes. $m_1 = 28$, $x_1=0.9221$; $m_2 = 29$, $x_2 = 0.0470$; $m_3=30$, $x_3 = 0.0309$.

Step3: Calculate the sum

$A_{avg}=28\times0.9221 + 29\times0.0470+30\times0.0309$
$=25.8188+1.363 + 0.927$
$=28.1088$

Answer:

$28.1088$