原子核的平均质量与原子序数（核言碎语175）

128 原子序数、中子数和核稳定性

Atomic number, Neutron Number, and Nuclear Stability

（https://www.nuclear-power.com/）

原子序数、中子数和核稳定性

Detail of Nuclide Chart.核素图的细节

Atomic nuclei consist of protons and neutrons, which attract each other through the nuclear force, while protons repel each other via the electric force due to their positive charge. These two forces compete, leading to various stability of nuclei. There are only certain combinations of neutrons and protons, which form stable nuclei.

原子核由质子和中子组成，它们通过核力相互吸引，而质子由于带正电荷而通过电场相互排斥。这两种力相互竞争，导致原子核具有不同的稳定性。只有特定的中子和质子组合才能形成稳定的原子核。

Neutrons stabilize the nucleus because they attract each other and protons, which helps offset the electrical repulsion between protons. As a result, as the number of protons increases, an increasing ratio of neutrons to protons is needed to form a stable nucleus. If there are too many or too few neutrons for a given number of protons, the resulting nucleus is not stable and undergoes radioactive decay. Unstable isotopes decay through various radioactive decay pathways, most commonly alpha decay, beta decay, or electron capture. Many other rare types of decay, such as spontaneous fission or neutron emission, are known. We should note that all of these decay pathways may be accompanied by the subsequent emission of gamma radiation. Pure alpha or beta decays are very rare.

中子稳定原子核是因为它们相互吸引并吸引质子，这有助于抵消质子之间的电排斥力。因此，当质子数量增加时，需要增加中子与质子的比例才能形成稳定的原子核。对于一定数量的质子，如果中子过多或过少，那么原子核就不稳定，就会发生放射性衰变。不稳定的同位素通过各种放射性衰变途径衰变，最常见的是α衰变、β衰变或电子俘获。许多其他罕见的衰变类型，如自发裂变或中子发射，是已知的。我们应该注意到，所有这些衰变途径都可能伴随着随后的伽马辐射的发射。纯粹的α衰变或β衰变是非常罕见的。

（待续）