Question

what does the atomic number represent?
a. the atomic mass of the element
b. the number of neutrons in an atom
c. the chemical reactivity of the element
d. the number of protons in the nucleus

Explanation:

The atomic number is defined as the number of protons in the nucleus of an atom. Let's analyze each option:

• Option a: Atomic mass is the sum of protons and neutrons, not the atomic number.
• Option b: The number of neutrons is not what the atomic number represents.
• Option c: Chemical reactivity is related to electron configuration, not directly to the atomic number (though atomic number affects electron configuration indirectly).
• Option d: By definition, the atomic number \(Z\) is equal to the number of protons in the nucleus.

Answer:

d. The number of protons in the nucleus