Multiple Choice
Copper has two isotopes. The Cu-63 isotope weighs 62.9296 amu and has 69.17% of the natural abundance. What is the atomic mass (in amu) of the second copper isotope if the average atomic mass of copper is 63.546 amu?
2. Atoms & Elements
Isotopes
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Which formula is used to calculate the percentage abundance of an isotope in a sample?
A
Percentage abundance = (Atomic number of the isotope / Total atomic number) x 100
B
Percentage abundance = (Mass of the isotope / Total mass of the sample) x 100
C
Percentage abundance = (Number of atoms of the isotope / Total number of atoms) x 100
D
Percentage abundance = (Volume of the isotope / Total volume of the sample) x 100
Verified step by step guidance1
Identify the concept of percentage abundance, which refers to the proportion of a specific isotope in a sample relative to the total number of isotopes present.
Understand that percentage abundance is calculated based on the number of atoms, not mass, volume, or atomic number.
The correct formula for percentage abundance is: \( \text{Percentage abundance} = \left( \frac{\text{Number of atoms of the isotope}}{\text{Total number of atoms}} \right) \times 100 \).
This formula calculates the ratio of the number of atoms of a specific isotope to the total number of atoms in the sample, then multiplies by 100 to convert it to a percentage.
Review the other options provided and recognize that they incorrectly use mass, volume, or atomic number, which are not appropriate for calculating percentage abundance of isotopes.
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