Atom, molecules, and Ions

Main article for this part is: nucleus
Binding energy required by the nucleon to escape from the core at various isotopes.
The nucleus consists of protons and neutrons are bound together at the center of the atom. Collectively, protons and neutrons are called nucleons (particles making up the core). Estimated core radii equal to \ begin {smallmatrix} 1.07 \ sqrt [3] {A} \ end {smallmatrix} fm, where A is the number of nucleons. [38] It is very small compared with the atomic radius. Nucleons are bound together by the force of attraction potential called the residual strong force. At distances smaller than 2.5 fm, this force is stronger than the electrostatic force which causes the protons repel each other. [39]
Atoms of the same chemical element have the same number of protons, called the atomic number. An element can have varying numbers of neutrons. This variation is referred to as isotopes. The number of protons and neutrons of an atom will determine the nuclide atom, while the number of neutrons relative to the number of protons determines the stability of atomic nuclei, with a particular isotope of the element will carry radioactive decay. [40]
Neutrons and protons are two different types of fermions. Pauli exclusion principle forbids the existence of identical fermions (such as multiple protons) occupy a same quantum physical state at the same time. Therefore, each proton in the nucleus of an atom should occupy different quantum states with energy level respectively. Pauli principle is also applicable to neutrons. This prohibition does not apply to protons and neutrons occupy the same quantum state. [41]
For atoms with low atomic number, atomic nuclei have more protons than neutrons could potentially fall into a lower energy state through radioactive decay that causes the number of protons and neutrons balanced. Therefore, the atom with the number of protons and neutrons are balanced more stable and less likely to decay. However, with increasing atomic number, repelling force between protons create neutrons of atomic nuclei requires a higher proportion of more to maintain stability. In the heaviest nuclei, the ratio of neutrons per proton is required to maintain the stability will be increased to 1.5. [41]Description of the process that produces nuclear fusion of deuterium nuclei (consisting of one proton and one neutron). A positron (e +) emitted simultaneously with the electron neutrino.
The number of protons and neutrons in atomic nuclei can be changed, although this requires a very high energy because of the strong force attractions. Nuclear fusion occurs when many atomic particles combine to form heavier nuclei. For example, at the core of the Sun, protons require approximately 3-10 keV energy to overcome the repulsive force between each other and merge into a single core. [42] Nuclear Fission is the opposite of the fusion process. In nulir fission, the nucleus is broken down into two smaller nuclei. This usually occurs through radioactive decay. The nucleus can also be changed via a high-energy subatomic particle bombardment. If this change the number of protons in the nucleus, the atom will change the element. [43] [44]
If the core mass after the fusion reaction is smaller than the sum of the initial mass of constituent particles, then the difference is caused by the release of radiant energy (eg gamma rays), as found in the mass-energy equivalence formula of Einstein, E = mc2, where m is the mass of lost and c is the speed of light. This deficit is part of the binding energies of the new core. [45]
Fusion of two nuclei that produce larger nuclei with lower atomic numbers than iron and nickel (total number of nucleons equal to 60) usually is exothermic, which means that this process releases energy. [46] is the energy release process which makes nuclear fusion the star can be maintained. For heavier nuclei, binding energy per nucleon in the nucleus began to decline. This means that the fusion process would be endothermic. [41]