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In chemistry, the term proton refers to the hydrogen ion, H +. Since the atomic number of hydrogen is 1, a hydrogen ion has no electrons and corresponds to a bare nucleus, consisting of a proton (and 0 neutrons for the most abundant isotope protium 1 1 H). The proton is a "bare charge" with only about 1/64,000 of the radius of a hydrogen atom ...
A model of an atomic nucleus showing it as a compact bundle of protons (red) and neutrons (blue), the two types of nucleons.In this diagram, protons and neutrons look like little balls stuck together, but an actual nucleus (as understood by modern nuclear physics) cannot be explained like this, but only by using quantum mechanics.
The proton-neutron (p-n) bound state, or p-n pair, is stable and ubiquitous in baryonic matter. [24] The p-n pair contributes implicitly to the top ten most abundant isotopes in the universe, eight of which contain equal numbers of protons and neutrons (see Oddo-Harkins rule and abundance of the elements).
8 O as an example: Its nucleus has eight protons filling the first three proton "shells", eight neutrons filling the first three neutron "shells", and one extra neutron. All protons in a complete proton shell have zero total angular momentum, since their angular momenta cancel each other. The same is true for neutrons.
The neutrons and protons in a nucleus form a quantum mechanical system according to the nuclear shell model. Protons and neutrons of a nuclide are organized into discrete hierarchical energy levels with unique quantum numbers. Nucleon decay within a nucleus can occur if allowed by basic energy conservation and quantum mechanical constraints.
Beta decay (and electron capture): these processes are regulated by the weak force, and result from a transformation of a neutron into a proton, or a proton into a neutron. The neutron to proton transition is accompanied by the emission of an electron and an antineutrino, while proton to neutron transition (except in electron capture) causes ...
The liquid drop model is one of the first models of nuclear structure, proposed by Carl Friedrich von Weizsäcker in 1935. [5] It describes the nucleus as a semiclassical fluid made up of neutrons and protons, with an internal repulsive electrostatic force proportional to the number of protons.
The masses of the proton and neutron are similar: for the proton it is 1.6726 × 10 −27 kg (938.27 MeV/c 2), while for the neutron it is 1.6749 × 10 −27 kg (939.57 MeV/c 2); the neutron is roughly 0.13% heavier. The similarity in mass can be explained roughly by the slight difference in masses of up quarks and down quarks composing the ...