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The mass of the neutron is greater than that of the proton by 1.293 32 MeV/c 2, [25] hence the neutron's mass provides energy sufficient for the creation of the proton, electron, and anti-neutrino. In the decay process, the proton, electron, and electron anti-neutrino conserve the energy, charge, and lepton number of the neutron. [ 26 ]
For 12 C, the isotopic mass is exactly 12, since the atomic mass unit is defined as 1/12 of the mass of 12 C. For other isotopes, the isotopic mass is usually within 0.1 u of the mass number. For example, 35 Cl (17 protons and 18 neutrons) has a mass number of 35 and an isotopic mass of 34.96885. [7]
In physics, the proton-to-electron mass ratio (symbol μ or β) is the rest mass of the proton (a baryon found in atoms) divided by that of the electron (a lepton found in atoms), a dimensionless quantity, namely: μ = m p /m e = 1 836.152 673 426 (32). [1]
A proton is a stable subatomic particle, symbol p, H +, or 1 H + with a positive electric charge of +1 e (elementary charge).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).
The proton and neutron have nearly the same mass (938 MeV), [16] and may be regarded as one particle, the nucleon N(938),with two different charge states (proton +1, and neutron 0). [17] The proton's N (938) ground state and ∆ + (1232) excited state have different shapes. [ 18 ]
If the mass difference between parent and daughter is less than this, a proton-rich nucleus may still convert protons to neutrons by the process of electron capture, in which a proton simply electron captures one of the atom's K orbital electrons, emits a neutrino, and becomes a neutron.
protons and neutrons have different masses, [7] [8] and different nuclides have different ratios of protons and neutrons. atomic masses are reduced, to different extents, by their binding energies. The ratio of atomic mass to mass number (number of nucleons) varies from 0.998 838 1346 (51) for 56 Fe to 1.007 825 031 898 (14) for 1 H.
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 ...