An element has three naturally occurring isotopes with the following masses and abundances (in parenthesis): 27.977 amu (0.9222); 28.974 amu (0.0469); 29.974 amu (0.0310). Calculate the atomic weight of the element.
A) 28.09 amu
B) 66.94 amu
C) 86.93 amu
D) 28.98 amu
E) 83.93 amu

Question

Quizplus · Accepted Answer

The atomic weight of the element can be calculated by multiplying the mass of each isotope by its relative abundance and then summing these products. Calculation: (27.977 amu * 0.9222) + (28.974 amu * 0.0469) + (29.974 amu * 0.0310) = 25.789 + 1.359 + 0.929 = 28.077 amu, which rounds to 28.09 amu.

An Element Has Three Naturally Occurring Isotopes with the Following