N

Nucleon

A = Z + N; same as mass number
Quick Reference
Formula / NotationA = Z + N; same as mass number
Also Known AsProton or neutron, nuclear particle, nucleon (proton/neutron)

What is Nucleon?

A collective term for the protons and neutrons that make up the atomic nucleus. The total number of nucleons equals the mass number of an atom. Strong nuclear forces bind nucleons together in the nucleus, overcoming electrostatic repulsion between protons.

Formula & Notation

A = Z + N; same as mass number

Other Names / Synonyms: Proton or neutron, nuclear particle, nucleon (proton/neutron)

Properties & Characteristics

A nucleon is a proton or neutron — the particles that make up the nucleus of an atom. Protons have charge +e; neutrons have no charge. Both have mass ≈ 1 amu (proton: 1.00728 amu; neutron: 1.00866 amu). The nucleon number (mass number, A) equals total protons + neutrons. Nucleons are held together in the nucleus by the strong nuclear force (range ~1 fm), which overcomes proton-proton electrostatic repulsion at short distances.

Uses & Applications

The nucleon concept is central to: writing nuclear equations (nucleon number conservation), calculating nuclear binding energies (mass defect: Δm = Z×m_p + N×m_n − m_nucleus), designing nuclear reactors (neutron moderation and absorption), nuclear medicine (producing neutron-rich isotopes by neutron bombardment in reactors), and particle physics research.

Safety Information

High-energy nucleons (protons and neutrons used in particle accelerators) are forms of ionising radiation causing biological damage. Neutrons from nuclear reactors and accelerators require polyethylene (hydrogenous) or water shielding for effective attenuation. Activation of materials by neutron bombardment produces radioactive nuclides.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Nucleon
Formula A = Z + N; same as mass number
Synonyms Proton or neutron, nuclear particle, nucleon (proton/neutron)

Frequently Asked Questions

A collective term for the protons and neutrons that make up the atomic nucleus. The total number of nucleons equals the mass number of an atom. Strong nuclear forces bind nucleons together in the nucleus, overcoming electrostatic repulsion between protons.

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