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Its mass is slightly less than the mass of a neutron and approximately 1836 times the mass of an electron (the proton-to-electron mass ratio). Protons and neutrons, each with a mass of approximately one atomic mass unit, are jointly referred to as nucleons (particles present in atomic nuclei). One or more protons are present in the nucleus of ...
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 negatively charged electron has a mass of about 1 / 1836 of that of a hydrogen atom. The remainder of the hydrogen atom's mass comes from the positively charged proton. The atomic number of an element is the number of protons in its nucleus. Neutrons are neutral particles having a mass slightly greater than that of the proton.
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).
If an atom has more electrons than protons, then it has an overall negative charge, and is called a negative ion (or anion). Conversely, if it has more protons than electrons, it has a positive charge, and is called a positive ion (or cation). The electrons of an atom are attracted to the protons in an atomic nucleus by the electromagnetic force.
As with electrons in the electron shell model, protons in the outermost shell are relatively loosely bound to the nucleus if there are only few protons in that shell, because they are farthest from the center of the nucleus. Therefore, nuclei which have a full outer proton shell will be more tightly bound and have a higher binding energy than ...
) "splits" into a proton (p), an electron (e −) and an electron antineutrino (ν e) (see picture). This occurs when one of the down quarks in the neutron (u d d) decays into an up quark by emitting a virtual W − boson, transforming the neutron into a proton (u u d). The W − boson then decays into an electron and an electron antineutrino. [72]
Comparison between the Nuclear Force and the Coulomb Force. a – residual strong force (nuclear force), rapidly decreases to insignificance at distances beyond about 2.5 fm, b – at distances less than ~ 0.7 fm between nucleons centres the nuclear force becomes repulsive, c – coulomb repulsion force between two protons (over 3 fm, force becomes the main), d – equilibrium position for ...