How do you calculate the atomic mass of magnesium?
79% magnesium-24, 10% magnesium-25, 11% magnesium-26
To calculate the atomic mass of an element, you need to consider the different isotopes of that element and their respective abundances.
In this case, magnesium has three isotopes: magnesium-24, magnesium-25, and magnesium-26. The percentages given represent the relative abundances of these isotopes.
To calculate the atomic mass, you need to multiply the mass of each isotope by its abundance (in decimal form) and then sum up the results.
Here's how you can calculate the atomic mass of magnesium:
1. Convert the percentages to decimal form:
- The abundance of magnesium-24 is 79%, so convert it to 0.79.
- The abundance of magnesium-25 is 10%, so convert it to 0.10.
- The abundance of magnesium-26 is 11%, so convert it to 0.11.
2. Determine the mass of each isotope:
- The atomic mass of magnesium-24 is 24 atomic mass units (AMU).
- The atomic mass of magnesium-25 is 25 AMU.
- The atomic mass of magnesium-26 is 26 AMU.
3. Multiply the mass of each isotope by its abundance:
- For magnesium-24: 0.79 × 24 = 18.96 AMU
- For magnesium-25: 0.10 × 25 = 2.50 AMU
- For magnesium-26: 0.11 × 26 = 2.86 AMU
4. Add up the results:
- 18.96 AMU + 2.50 AMU + 2.86 AMU = 24.32 AMU
Therefore, the atomic mass of magnesium is approximately 24.32 atomic mass units (AMU).