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Arsenic is a common n-type dopant in semiconductor electronic devices. It is also a component of the III–V compound semiconductor gallium arsenide. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining with the ...
Of particular importance is carbon because its formation from He is a bottleneck in the entire process. Carbon is produced by the triple-alpha process in all stars. Carbon is also the main element that causes the release of free neutrons within stars, giving rise to the s-process, in which the slow absorption of neutrons converts iron into ...
Clayton calculated the first time-dependent models of the s-process in 1961 [15] and of the r-process in 1965, [16] as well as of the burning of silicon into the abundant alpha-particle nuclei and iron-group elements in 1968, [17] [18] and discovered radiogenic chronologies [19] for determining the age of the elements.
Aston discovered the whole number rule, that the masses of all the particles have whole number relationships to oxygen-16, [18] which he took to have a mass of exactly 16. [4] (Today the whole-number rule is expressed in multiples of an atomic mass unit (amu) relative to carbon-12. [19]). Significantly, the one exception to this rule was ...
Protons and neutrons in an atom's nucleus can be arranged in different configurations, creating nuclear isomers. KTSdesign/SciencePhotoLibrary via Getty ImagesNobel laureate Otto Hahn is credited ...
Supernova nucleosynthesis is the nucleosynthesis of chemical elements in supernova explosions.. In sufficiently massive stars, the nucleosynthesis by fusion of lighter elements into heavier ones occurs during sequential hydrostatic burning processes called helium burning, carbon burning, oxygen burning, and silicon burning, in which the byproducts of one nuclear fuel become, after ...
Once temperatures are lowered, out of every 16 nucleons (2 neutrons and 14 protons), 4 of these (25% of the total particles and total mass) combine quickly into one helium-4 nucleus. This produces one helium for every 12 hydrogens, resulting in a universe that is a little over 8% helium by number of atoms, and 25% helium by mass.
Arsenic (33 As) has 32 known isotopes and at least 10 isomers. Only one of these isotopes, 75 As, is stable; as such, it is considered a monoisotopic element. The longest-lived radioisotope is 73 As with a half-life of 80 days.