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Sulfur (16 S) has 23 known isotopes with mass numbers ranging from 27 to 49, four of which are stable: 32 S (95.02%), 33 S (0.75%), 34 S (4.21%), and 36 S (0.02%). The preponderance of sulfur-32 is explained by its production from carbon-12 plus successive fusion capture of five helium-4 nuclei, in the so-called alpha process of exploding type II supernovas (see silicon burning).
Of the 25 known isotopes of sulfur, four are stable. [1] In order of their abundance, those isotopes are 32 S (94.93%), 34 S (4.29%), 33 S (0.76%), and 36 S (0.02%). [2] The δ 34 S value refers to a measure of the ratio of the two most common stable sulfur isotopes, 34 S: 32 S, as measured in a sample against that same ratio as measured in a known reference standard.
With the discovery of oxygen isotopes in 1929, a situation arose where chemists based their calculations on the average atomic mass (atomic weight) of oxygen whereas physicists used the mass of the predominant isotope of oxygen, oxygen-16. This discrepancy became undesired and a unification between the chemistry and physics was necessary. [13]
In the atomic symbol of 32 S, the number 32 refers to the mass of each sulfur atom in daltons, the result of the 16 protons and 16 neutrons of 1 dalton each that make up the sulfur nucleus. The three rare stable isotopes of sulfur are 34 S (4.2% of natural sulfur), 33 S (0.75%), and 36 S (0.015%). [4]
Sulfur isotope ratios are almost always expressed as ratios relative to 32 S due to this major relative abundance (95.0%). Sulfur isotope fractionations are usually measured in terms of δ 34 S due to its higher abundance (4.25%) compared to the other stable isotopes of sulfur, though δ 33 S is also sometimes measured.
Isotope geochemistry is an aspect of geology based upon the study of natural variations in the relative abundances of isotopes of various elements.Variations in isotopic abundance are measured by isotope-ratio mass spectrometry, and can reveal information about the ages and origins of rock, air or water bodies, or processes of mixing between them.
The third book in the Yarros’ “Empyrean” series comes out in January from Entangled Publishing. The follow-up to “Fourth Wing” and “Iron Flame” swaps Basgiath War College lessons for ...
In physics, natural abundance (NA) refers to the abundance of isotopes of a chemical element as naturally found on a planet. The relative atomic mass (a weighted average, weighted by mole-fraction abundance figures) of these isotopes is the atomic weight listed for the element in the periodic table. The abundance of an isotope varies from ...