Nucleon
Definition and meaning of Nucleon in chemistry.
Nucleon is a proton or neutron, the subatomic particles that together form the nucleus of an atom. Nucleons account for nearly all of an atom's mass.
In more detail
Protons carry a positive electric charge, while neutrons are electrically neutral. Both nucleon types have approximately equal mass (about 1 atomic mass unit each) and are held together in the nucleus by the strong nuclear force, one of the four fundamental interactions in nature. The total count of nucleons is called the mass number (A) and determines which isotope of an element you have. For example, carbon-12 contains 6 protons and 6 neutrons (A = 12), while carbon-13 contains 6 protons and 7 neutrons (A = 13), even though both are carbon.
Key facts
| Field | General Chemistry |
|---|---|
| Components | Protons and neutrons |
| Strong force | Binds nucleons in the nucleus |
| Mass contribution | Over 99.9% of atom's total mass |
An oxygen-16 nucleus contains 8 protons and 8 neutrons, making the mass number A = 16 and giving it a total of 16 nucleons.
Frequently asked questions
Is an electron a nucleon?
No. Nucleons (protons and neutrons) exist only in the nucleus; electrons orbit outside the nucleus.
Why don't protons push each other apart in the nucleus?
The strong nuclear force, which acts only at very short distances, overcomes the electrostatic repulsion between positively charged protons.