3 ms·

One could argue that neutron stars are nuclea... If so, at least nuclea production doesn't stop any time soon. Probably you wouldn't call it an atom though...

adrian_b 2y ago
The neutron is really an additional chemical element, the element with Z=0. It belongs in the group of noble gases, together with helium, neon, argon, krypton, xenon and radon. Like radon, it is unstable, but also like radon it is widespread in nature as a product of radioactive decays. The element with Z=0 has multiple isotopes, like any other chemical element. Unlike for any other element, the possibility of gravitational stabilization makes the number of its stable isotopes potentially infinite. The neutron stars can be seen as belonging to the isotopes of the chemical element with Z=0.
- WantonQuantum 2y ago
  Interestingly, neutron stars do contain a small percentage of protons.
  - adrian_b 2y ago
    However, those protons are not stable. Their concentration is the result of the equilibrium between neutrons that decay into proton and electron pairs and proton-electron pairs that recombine into neutrons. The complete neutron star still behaves like a giant nucleus with null electric charge, i.e. with Z=0.
skykooler 2y ago
Surely it's not an atom because it doesn't have electron orbitals? (Although I suppose electrons could orbit it, in the classical sense rather than the quantum sense!)
- adrian_b 2y ago
  It is the limit case of a neutral atom, like the neutral atoms of the noble gases, which has 0 electrons instead of having 2 electrons, 10 electrons etc. From a big enough distance, there is no essential difference between neutrons and the neutral atoms of any noble gas. They all are neutral particles which do not react chemically. The weak van der Waals forces between the atoms of the noble gases decrease from radon to helium and neutron fits in this progression. At extremely small distances between neutrons, weak attraction forces appear between them, which are analogous to the van der Waals forces generated by residual electromagnetic interactions, but they are generated by residual strong nuclear interactions. A positive hydrogen ion has 0 electrons too, the same as a doubly-ionized helium atom, triple-ionized lithium atom, etc. The relationship between neutrons and these ions is the same as for instance between helium and lithium ions, beryllium ions, boron ions, etc. Calling a neutron as the limit case of an atom is a choice, but this choice simplifies many descriptions of things related to atoms and ions, in the same way as including zero in the cardinal numbers simplifies the descriptions of many things related to numbers, because there is no longer any need to describe separately some special cases.

adrian_b 2y ago

The neutron is really an additional chemical element, the element with Z=0. It belongs in the group of noble gases, together with helium, neon, argon, krypton, xenon and radon. Like radon, it is unstable, but also like radon it is widespread in nature as a product of radioactive decays. The element with Z=0 has multiple isotopes, like any other chemical element. Unlike for any other element, the possibility of gravitational stabilization makes the number of its stable isotopes potentially infinite. The neutron stars can be seen as belonging to the isotopes of the chemical element with Z=0.

WantonQuantum 2y ago
Interestingly, neutron stars do contain a small percentage of protons.
- adrian_b 2y ago
  However, those protons are not stable. Their concentration is the result of the equilibrium between neutrons that decay into proton and electron pairs and proton-electron pairs that recombine into neutrons. The complete neutron star still behaves like a giant nucleus with null electric charge, i.e. with Z=0.

skykooler 2y ago

Surely it's not an atom because it doesn't have electron orbitals? (Although I suppose electrons could orbit it, in the classical sense rather than the quantum sense!)

adrian_b 2y ago
It is the limit case of a neutral atom, like the neutral atoms of the noble gases, which has 0 electrons instead of having 2 electrons, 10 electrons etc. From a big enough distance, there is no essential difference between neutrons and the neutral atoms of any noble gas. They all are neutral particles which do not react chemically. The weak van der Waals forces between the atoms of the noble gases decrease from radon to helium and neutron fits in this progression. At extremely small distances between neutrons, weak attraction forces appear between them, which are analogous to the van der Waals forces generated by residual electromagnetic interactions, but they are generated by residual strong nuclear interactions. A positive hydrogen ion has 0 electrons too, the same as a doubly-ionized helium atom, triple-ionized lithium atom, etc. The relationship between neutrons and these ions is the same as for instance between helium and lithium ions, beryllium ions, boron ions, etc. Calling a neutron as the limit case of an atom is a choice, but this choice simplifies many descriptions of things related to atoms and ions, in the same way as including zero in the cardinal numbers simplifies the descriptions of many things related to numbers, because there is no longer any need to describe separately some special cases.