alleryStart learning →What does the atomic number Z represent?
AThe number of neutrons in a nucleus
BThe number of protons in a nucleus
CThe total number of nucleons in a nucleus
DThe number of electron shells in an atom
Answer & Solution
Correct answer: B. The number of protons in a nucleus
1. The atomic number Z is defined as the number of protons within a nucleus.
2. This value determines which element the atom is, since every element has a fixed Z.
3. Neutron count is represented separately by N, and total nucleons by the mass number A.
4. Electron shells are a separate atomic feature not represented by Z.
5. So the number of protons is correct.
_Source: OpenStax Physics (CC BY 4.0), Ch 22 "The Atom", section 22.2 Nuclear Forces and Radioactivity_
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