Question

1. calculate the relative atomic mass for germanium

$_{32}^{70}ge = 20.84\\%$
$_{32}^{72}ge = 27.54\\%$
$_{32}^{73}ge = 7.73\\%$
$_{32}^{74}ge = 36.28\\%$
$_{32}^{76}ge = 7.61\\%$

1. calculate the relative atomic mass for selenium

$_{34}^{74}se = 0.89\\%$
$_{34}^{76}se = 9.37\\%$
$_{34}^{77}se = 7.63\\%$
$_{34}^{78}se = 23.77\\%$
$_{34}^{80}se = 49.61\\%$
$_{34}^{82}se = 8.73\\%$

Explanation:

Step1: Recall the formula for relative atomic mass

The relative atomic mass ($A_r$) of an element is calculated as $A_r=\sum_{i} (m_i\times p_i)$, where $m_i$ is the mass - number of the isotope and $p_i$ is the percentage abundance of the isotope (expressed as a decimal).

Step2: Calculate the relative atomic mass of Germanium

For Germanium:
\[

$$\begin{align*} A_{r}(Ge)&=(70\times0.2084)+(72\times0.2754)+(73\times0.0773)+(74\times0.3628)+(76\times0.0761)\\ &=14.588 + 19.8288+5.6429 + 26.8472+5.7836\\ &=72.6905\approx72.69 \end{align*}$$

\]

Step3: Calculate the relative atomic mass of Selenium

For Selenium:
\[

$$\begin{align*} A_{r}(Se)&=(74\times0.0089)+(76\times0.0937)+(77\times0.0763)+(78\times0.2377)+(80\times0.4961)+(82\times0.0873)\\ &=0.6586+7.1212 + 5.8751+18.5406+39.688+7.1586\\ &=79.0421\approx79.04 \end{align*}$$

\]

Answer:

The relative atomic mass of Germanium is approximately $72.69$ and the relative atomic mass of Selenium is approximately $79.04$