The atomic mass number is equal to the sum of the
A) neutrons and isotopes
B) neutrons and electrons
C) neutrons and protons
D) protons, neutrons, and electrons
E) protons only

Question

Quizplus · Accepted Answer

The atomic mass number of an atom is equal to the sum of its protons and neutrons in the nucleus. Electrons do not contribute significantly to the mass of an atom, so option D is incorrect. Option A is incorrect because isotopes refer to atoms of the same element with different numbers of neutrons, and they are not added to the atomic mass number. Option B is incorrect because electrons do not contribute to the mass number. Option E is incorrect because it only includes the number of protons, not the number of neutrons in the nucleus.

The Atomic Mass Number Is Equal to the Sum of the