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词汇 Abundance of elements
分类 英语词汇 英语翻译词典
释义

Abundance of elements

原声例句
Crash Course 天文篇

The Big Bang model predicts certain abundances of elements — ratios of them, compared to hydrogen — and that's just what we see in the Universe at large.

大爆炸模型预测了元素的丰度——元素与氢的比值——这正是我们在整个宇宙中所看到的。

英语百科

Abundance of the chemical elements

Estimated proportions of matter, dark matter and dark energy in the universe according to 5 year WMAP data. Only the fraction of the mass and energy in the universe labeled
Estimated abundances of the chemical elements in the Solar system. Hydrogen and helium are most common, from the Big Bang. The next three elements (Li, Be, B) are rare because they are poorly synthesized in the Big Bang and also in stars. The two general trends in the remaining stellar-produced elements are: (1) an alternation of abundance in elements as they have even or odd atomic numbers (the Oddo-Harkins rule), and (2) a general decrease in abundance, as elements become heavier. Iron is especially common because it represents the minimum energy nuclide that can be made by fusion of helium in supernovae.
Periodic table showing the cosmogenic origin of each element
Abundance (atom fraction) of the chemical elements in Earth's upper continental crust as a function of atomic number. The rarest elements in the crust (shown in yellow) are the most dense. They were further rarefied in the crust by being siderophile (iron-loving) elements, in the Goldschmidt classification of elements. Siderophiles were depleted by being relocated into the Earth's core. Their abundance in meteoroid materials is relatively higher. Additionally, tellurium and selenium have been depleted from the crust due to formation of volatile hydrides.

The abundance of a chemical element is a measure of the occurrence of the element relative to all other elements in a given environment. Abundance is measured in one of three ways: by the mass-fraction (the same as weight fraction); by the mole-fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases); or by the volume-fraction. Volume-fraction is a common abundance measure in mixed gases such as planetary atmospheres, and is similar in value to molecular mole-fraction for gas mixtures at relatively low densities and pressures, and ideal gas mixtures. Most abundance values in this article are given as mass-fractions.

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