Search results
Results from the WOW.Com Content Network
The electrons are negatively charged, and this opposing charge is what binds them to the nucleus. If the numbers of protons and electrons are equal, as they normally are, then the atom is electrically neutral as a whole. If an atom has more electrons than protons, then it has an overall negative charge and is called a negative ion (or anion ...
A nuclide is a species of an atom with a specific number of protons and neutrons in the nucleus, for example, carbon-13 with 6 protons and 7 neutrons. The nuclide concept (referring to individual nuclear species) emphasizes nuclear properties over chemical properties, whereas the isotope concept (grouping all atoms of each element) emphasizes chemical over nuclear.
In contrast, the proton numbers for which there are no stable isotopes are 43, 61, and 83 or more (83, 90, 92, and perhaps 94 have primordial radionuclides). [3] This is related to nuclear magic numbers , the number of nucleons forming complete shells within the nucleus, e.g. 2, 8, 20, 28, 50, 82, and 126.
The darker more stable isotope region departs from the line of protons (Z) = neutrons (N), as the element number Z becomes larger. Isotopes are nuclides with the same number of protons but differing numbers of neutrons; that is, they have the same atomic number and are therefore the same chemical element. Isotopes neighbor each other vertically.
Protons and electrons both carry an intrinsic spin of 1 / 2 ħ, and the isotopes of the same species were found to have either integer or fractional spin. By the hypothesis, isotopes would be composed of the same number of protons, but differing numbers of neutral bound proton+electron "particles".
The difference of the actual isotopic mass minus the mass number of an atom is known as the mass excess, [8] which for 35 Cl is –0.03115. Mass excess should not be confused with mass defect which is the difference between the mass of an atom and its constituent particles (namely protons, neutrons and electrons). There are two reasons for mass ...
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 ...
3 He is the only stable isotope other than 1 H with more protons than neutrons. (There are many such unstable isotopes; the lightest are 7 Be and 8 B.) There is only a trace (~2ppm) [ 16 ] of 3 He on Earth, mainly present since the formation of the Earth, although some falls to Earth trapped in cosmic dust. [ 7 ]