Isotopes decomposition

From the isotopic decomposition of normal H one finds that the mass-i isotope, 1H, is overwhelmingly its most abundant isotope. It is 99.985% of all H isotopes in the H20 (water) of the oceans. From astronomical observations it is known that 71% of all of the nucleons in the universe are in its H atoms that is, when elements are compared by total mass rather than by numbers, 71% of the mass (visible mass, that is) of the universe is hydrogen. If the comparison is made by numbers of atoms instead of by the relative masses of the elements, hydrogen atoms are 90% of all atoms in the universe ... 

From the isotopic decomposition of normal H one finds that the mass-2 isotope, 2H, or D (for deuterium) as it is also written, is relatively rare. On Earth it constitutes only 0.015% °f all H isotopes. This makes it 6670 times less abundant than 1H. This information comes from the isotopic analysis of sea water however, deuterium is even more rare in the universe Modern observations of the interstellar gas reveal it to be ten times less abundant relative to H than it is in sea water. This makes the deuterium abundance of Earth the first great isotopic anomaly namely, that D in sea water has been enriched tenfold by the historical processes by which the Earth s oceans were formed from the initial interstellar matter from which the solar system was built. 

From the isotopic decomposition ofnormal He one finds thatthe mass-3 isotope, 3He, is quite rare relative to 4He. It is 0.0142% of all helium in solar gases at the time the Sun was forming, as recorded in planetary gases trapped within gas-rich meteorites that formed in the primitive solar disk. It is somewhat larger, 0.0166% in the helium in Jupiter s atmosphere, which could be a better measure of initial 3He/4He. But3He is about 100 times more rare in the Earth s atmosphere (relative to 4He) because the history ofradioactive decay of uranium in the Earth (see the Rutherford anecdote above) has enriched our atmosphere in daughter 4He. 

From the isotopic decomposition of normal He one finds that the mass-4 isotope, 4He, is 99.986% of all helium. It is the second most abundant nucleus in the universe Modern observations of the interstellar gas reveal it to be 10.3 times less abundant than hydrogen. The elemental abundance is He = 2.72 x 109 per million silicon atoms in solar-system matter. 

From the isotopic decomposition ofnormal lithium onefinds thatthemass-6 isotope, 6Li, is the lesser abundant of lithium s two isotopes 7.5% of terrestrial Li. Lithium presents some of the most interesting abundance questions in astrophysics (see also 7Li). Using the total abundance of elemental Li = 57.1 per million silicon atoms in solar-system matter, this isotope has... 

Carbon is the fourth most abundant element in the universe. Its abundance in the Sun is about one-half that of oxygen, butreveals differing ratios to oxygen in other stars and in nebulae. The most abundant isotope of carbon, 12C, is the fourth most abundant nucleus in the universe. The two most abundant, 2H and 4He, are remnants of the Big Bang, whereas l60, the third most abundant, and 12C are created during the evolution of stars. Carbon ranks therefore as one of the great successes of stellar nucleosynthesis. The evolution of stars makes evident why this is so. From the isotopic decomposition of normal carbon one finds that the mass-12 isotope, 12C, is 98.9% of all C isotopes. 

Carbon is the fourth mostabundant elementin the universe. From the isotopic decomposition of normal carbon one finds that the mass-13 isotope, 13C, is 1.11% of all C... 

From the isotopic decomposition ofterrestrial nitrogen one finds thatthe mass-14 isotope, 14N, is 99.63% of all N isotopes, essentially the entire N abundance. (See 15N for evidence from Jupiter for an even smaller 15N fraction in the solar system.) Using the total abundance of elemental N = 3.13 million per million silicon atoms (he. 3.13 times more abundant than Si) in solar-system matter,... 

Nitrogen is the sixth most abundant element in the universe, butits mass-15 isotope is but the 30th mostabundantisotope. From the isotopic decomposition of atmospheric... 

From the isotopic decomposition of normal silicon one finds thatthe mass-28 isotope, 2 Si, is the most abundant of the three stable Si isotopes 92.23 % of all Si. Using one million silicon atoms, the common cosmochemical standard in solar-system matter,... 

From the isotopic decomposition of normal sulfur one finds that the mass-32 isotope, 32S, is the most abundant of the stable S isotopes 95.02% of all S. On the scale where one million silicon atoms is taken as the standard for solar-system matter, this isotope has... 

Argon is the third mostabundant of the noble gases. From the isotopic decomposition of solar-wind Ar one finds that the mass-38 isotope,38 Ar, is the second mostabundant of Ar isotopes in the universe. In the Earth s atmosphere,40 Ar happens to be the most abundant owing to its peculiar origin on Earth as the daughter of radioactive 4°K. 3 Ar comprises 15.8% of all the Ar isotopes in the Sun. Using the total abundance of elemental Ar = 1.01 x lo5 per million silicon atoms in the Sun, this isotope has... 

From the isotopic decomposition of normal K one finds that the mass-40 isotope, 4°K, is much the rarest of K isotopes in the universe. It is about 8000 times less abundant than 39K, the most abundant of the three naturally occurring isotopes. But it was not always so rare. At the birth of the solar system, 4°K was 12.4 times more abundant than it is today on Earth, where its radioactive halflife has reduced its abundance by halfevery 1.28 billion years. In the Earth s atmosphere, 40 Ar happens to be the most abundant... 

From the isotopic decomposition of normal calcium one finds that the mass-40 isotope,40 Ca, is the mostabundant of the stable calcium isotopes 96.94% ofall Ca.On... 

From the isotopic decomposition of normal titanium one finds that the mass-49 isotope, 49Ti, is one of the four lesser abundant of the stable titanium isotopes 5.5%... 

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