Hydrogen universal abundance

This is very fine and beautiful, but when are we going to explain why hydrogen rather than iron heads the list of universal abundances We have already whispered the answer, but rather discreetly. Having determined how iron is produced, the time has come to deal with this question. 

Named by Lavoisier, hydrogen is the most abundant of all elements in the universe. The heavier elements were originally made from Hydrogen or from other elements that were originally made from Hydrogen. 

Except for hydrogen, helium is the most abundant element found through out the universe. Helium is extracted from natural gas. In fact, all natural gas contains at least trace quantities of helium. 

Iron is a relatively abundant element in the universe. It is found in the sun and many types of stars in considerable quantity. Its nuclei are very stable. Iron is a principal component of a meteorite class known as siderites and is a minor constituent of the other two meteorite classes. The core of the earth — 2150 miles in radius — is thought to be largely composed of iron with about 10 percent occluded hydrogen. The metal is the fourth most abundant element, by weight that makes up the crust of the earth. 

As the universe expanded it cooled and the positively charged protons and helium nuclei com bined with electrons to give hydrogen and helium atoms Together hydrogen and helium account for 99% of the mass of the universe and 99 9% of its atoms Hydrogen is the most abundant element 88 6% of the atoms in the universe are hydrogen and 11 3% are helium... 

Helium is the second most abundant element in the universe (76% H, 23% He) as a result of its synthesis from hydrogen (p. 9) but, being too light to be retained by the earth s gravitational field, all primordial helium has been lost and terrestrial helium, like argon, is the result of radioactive decay ( He from a-decay of heavier elements, " °Ar from electron capture by... 

Hydrogen is the most abundant element in the universe and is found in a variety of compounds, including hydrocarbons (e.g., fossil fuels or biomass) and water. Since free hydrogen does not occur naturally on earth in large quantities, it must be produced from hydrogen-containing compounds. 

Hydrogen is the lightest known element. Although only found in the free state in trace amounts, it is the most abundant element in the universe and is present in a combined form with other elements. Water, natural gas, crude oils, hydrocarbons, and other organic fossil materials are major sources of hydrogen. 

Bodner and Domin (2000) demonstrated the inability of many university students to interpret abbreviated structural portrayals with some atoms implied, rather than shown. The students were asked to predict the major products of the reaction of bromine with methylcyclopentane portrayed as in Fig. 1.2, and to estimate the ratio of the products if bromine radicals were just as likely to attack one hydrogen atom as another. Most of the 200 students predicted three products, with a relative abundance 3 2 2 (Fig. 1.4). 

Hydrogen is the most abundant element in the universe, constituting roughly 75% of the universe s normal mass and 90% of the atoms present in the universe. Elemental hydrogen was first described by the legendary Swiss alchemist Paracelsus (1493-1541), and later in 1671 by Robert Boyle, but was... 

I In the universe as a whole, including our sun and all the stars, hydrogen is probably the most abundant element. The stars are made mostly of hydrogen approximately 90 percent of our sun is hydrogen. 

Fig. 1. Evolution of 3He/H in the solar neighborhood, computed without extra-mixing (upper curve) and with extra-mixing in 90% or 100% of stars M < 2.5 M (lower curves). The two arrows indicate the present epoch (assuming a Galactic age of 13.7 Gyr) and the time of formation of the solar system 4.55 Gyr ago. Symbols and errorbars show the 3He/H value measured in meteorites (empty squares) Jupiter s atmosphere (errorbar) the local ionized ISM (filled triangle) the local neutral ISM (filled circle) the sample of simple Hll regions (empty circles). Data points have been slightly displaced for clarity. The He isotopic ratios has been converted into abundances relative to hydrogen assuming a universal ratio He/H= 0.1. See text for references.

The majority of the Universe is made from hydrogen and helium produced during the Big Bang, although some He has been made subsequently. The relative cosmic abundance of some of the elements relevant to the formation of life is given in Table 1.2, with all elements heavier than H, He and Li made as a result of fusion processes within stars, as we shall see later. The cosmic abundance is assumed to be the same as the composition of the Sun. 

Detection of hydrogen is a particularly important problem for astrochemists because to a first approximation all visible matter is hydrogen. The hydrogen molecule is the most abundant molecule in the Universe but it presents considerable detection problems due to its structure and hence spectroscopy. Hydrogen does not possess a permanent dipole moment and so there is no allowed rotation or vibration spectrum and all electronic spectrum transitions are in the UV and blocked by the atmosphere. The launch of the far-UV telescope will allow the detection of H2 directly but up to now its concentration has been inferred from other measurements. The problem of detecting the H atom, however, has been solved using a transition buried deep in the hyperflne structure of the atom. 

Hydrogen is the most abundant element in the universe, accounting for 90% (by wt) of the universe. Owing to its high reactivity it is not found commonly in its pure form, but rather in compounds... 

Hydrogen is the most abundant element in the universe. Worldwide consumption exceeds 400xl0g m3 each day, with 20% of this total attributed to the United States. However, despite widespread commercial use, not all of hydrogen s flammability limits are known. 

Hydrogen is the most abundant chemical element in the universe, and in its various atomic and molecular forms furnishes a sensitive test of all of experimental, theoretical and computational methods. Vibration-rotational spectra of dihydrogen in six isotopic variants constituting all binary combinations of H, D and T have nevertheless been recorded in Raman scattering, in either spontaneous or coherent processes, and spectra of HD have been recorded in absorption. Despite the widely variable precision of these measurements, the quality of some data for small values of vibrational quantum number is still superior to that of data from electronic spectra [106], almost necessarily measured in the ultraviolet region with its concomitant large widths of spectral lines. After collecting 420... 

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