Answer:
See below.
Step-by-step explanation:
OK, let's consider lithium. It consists of 7.59 % ⁶Li and 92.41 % ⁷Li and has an atomic mass of 6.94 u.
The atomic mass of ⁶Li is 6.015 u, and that of ⁷Li is 7.016 u.
What would the atomic mass of lithium be if it consisted of 87.34 % ⁶Li and 12.66 % ⁷Li?
The atomic mass of X is the weighted average of the atomic masses of its isotopes.
We multiply the atomic mass of each isotope by a number representing its relative importance (e.g., its fraction of the total).
Set up a table for easy calculation
0.8734 × 6.015 u = 5.254 u
0.1266 × 7.016 u = 0.8882 u
TOTAL = 6.142 u
The atomic mass of lithium would be 6.14 u instead of 6.94 u.
