The number of protons in an atom is represented by an element's
A)mass number.
B)atomic number.
C)atomic mass.
D)valence number.
E)None of these choices.

Question

Quizplus · Accepted Answer

The atomic number of an element represents the number of protons in its nucleus. Therefore, the correct choice is atomic number. The mass number is the sum of protons and neutrons in the nucleus, while the atomic mass is the average mass of isotopes of an element. Valence number is related to the number of electrons in the outermost shell of an atom.

The Number of Protons in an Atom Is Represented by an Element's