To calculate the atomic mass of gallium, we'll use the weighted average formula:

$\text{Atomic Mass} = (\text{Fractional Abundance of Isotope 1} \times \text{Mass of Isotope 1}) + (\text{Fractional Abundance of Isotope 2} \times \text{Mass of Isotope 2})$

Given:

• Isotope 1: Ga-69 with a mass of 68.926 amu and a percent abundance of 60.108%.
• Isotope 2: Ga-71 with a mass of 70.925 amu and a percent abundance of 39.892%.

First, convert the percent abundances to fractional abundances:

• Fractional abundance of Ga-69 = $\frac{60.108}{100} = 0.60108$
• Fractional abundance of Ga-71 = $\frac{39.892}{100} = 0.39892$

Now, substitute these values into the formula:

$\text{Atomic Mass} = (0.60108 \times 68.926) + (0.39892 \times 70.925)$

Calculate each term:

$0.60108 \times 68.926 = 41.4421 \text{ amu}$ $0.39892 \times 70.925 = 28.2943 \text{ amu}$

Finally, add these two results together to find the atomic mass:

$\text{Atomic Mass} = 41.4421 + 28.2943 = 69.7364 \text{ amu}$

Therefore, the atomic mass of gallium is approximately 69.74 amu.

Would you like further details or have any questions?

Here are some related questions to consider:

1. How do isotopes affect the physical and chemical properties of elements?
2. What role does atomic mass play in determining the molar mass of a compound?
3. How does the atomic mass of gallium compare to other elements in the same group?
4. How can the atomic mass of gallium be used in calculating the mass of a sample of gallium?
5. What are some applications of gallium and how does its isotopic composition impact these uses?

Tip: When dealing with isotopic abundances, always check that the sum of all fractional abundances equals 1. This ensures accuracy in your calculations.