An element has two naturally occuring isotopes with the following masses and abundances...what is the atomic mass of this element?

Question

ISOTOPE1

- Isotopic mass (amu) = 49.9472

- Fractional abundance = 2.500 × 10^-3

ISOTOPE2

- Isotopic mass (amu) = 50.9440

- Fractional abundance = 0.9975

...part (b) What is the identity of the element?

Answer 1

(a) The atomic mass will be the weighted average of the isotopes. Note that ~99% is isotope 2, so we should expect the atomic mass to be very close to 50.9440. This is calculated as follows:

atomic mass = (49.9472)(2.500x10^-3) + (50.9440)(0.9975)

atomic mass = 0.12487 + 50.82 = 50.94

(b) The element is vanadium (V)