Isotopes of an element vary in mass because of differing numbers of:
A)Protons
B)Neutrons
C)Electrons
D)Protons and neutrons
E)Protons and electrons

Question

Quizplus · Accepted Answer

Isotopes of an element have the same number of protons (which defines the element), but they differ in the number of neutrons in their nuclei. This results in a difference in mass between isotopes. Electrons also have mass, but the difference in numbers of electrons is much smaller and does not contribute significantly to the mass difference between isotopes.

Isotopes of an Element Vary in Mass Because of Differing