Practice question · Numerical answer
Chlorine is 75.77 % chlorine-35 (mass 35 u) and 24.23 % chlorine-37 (mass 37 u). Compute its average atomic mass in u, to two decimal places.
Hints
- Weight each isotope mass by its fractional abundance and add.
- Compute 0.7577 x 35 + 0.2423 x 37.
Show the answer
35.48 (answers within ±0.03 count)
Why
u. The value sits near 35 because the lighter isotope dominates the population.
Practise Atomic Models and Isotopes
The app has 4 more questions on this lesson, and keeps your place in the course. Chemistry I is free to start.
More questions on Atomic Models and Isotopes
- Almost all alpha particles passed straight through the gold foil, but about 1 in 8000 rebounded. What does…
- An isotope has mass number A = 56 and atomic number Z = 26. How many neutrons does its nucleus contain?
- Two isotopes of the same element show almost identical chemical behaviour.
- Match each subatomic particle to its defining property.
- Which statements about isotopes are correct?
- The periodic table lists the atomic mass of chlorine as 35.45 u, yet no single chlorine atom possesses this…
- Why could Thomson's plum-pudding model not survive the gold-foil result?
- Place these atomic models and discoveries in chronological order.