Abundance Of The Chemical Elements
The abundance of a chemical element measures how relatively common (or rare) the element is, or how much of the element is present in a given environment by comparison to all other elements. Abundance may be variously measured by the mass-fraction (the same as weight fraction), or mole-fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases), or by volume-fraction. Measurement by volume-fraction is a common abundance measure in mixed gases such as planetary atmospheres, and is close to molecular mole-fraction for ideal gas mixtures (i.e., gas mixtures at relatively low densities and pressures).
For example, the mass-fraction abundance of oxygen in water is about 89%, because that is the fraction of water's mass which is oxygen. However, the mole-fraction abundance of oxygen in water is only 33% because only 1 atom of 3 in water is an oxygen atom. In the universe as a whole, and in the atmospheres of gas-giant planets such as Jupiter, the mass-fraction abundances of hydrogen and helium are about 74% and 23–25% respectively, while the (atomic) mole-fractions of these elements are closer to 92% and 8%. However, since hydrogen is diatomic while helium is not, in the conditions of Jupiter's outer atmosphere, the molecular mole-fraction (fraction of total gas molecules, or fraction of atmosphere by volume) of hydrogen in the outer atmosphere of Jupiter is about 86%, and for helium, 13%.
Most abundances in this article are given as mass-fraction abundances.
Read more about Abundance Of The Chemical Elements: Abundance of Elements in The Universe, Abundance of Elements in The Earth, Human Body Elemental Abundance
Famous quotes containing the words abundance of the, abundance of, abundance, chemical and/or elements:
“...out of the abundance of the heart the mouth speaks.”
—Bible: New Testament, Matthew 12:34.
“Take care! Be on your guard against all kinds of greed; for one’s life does not consist in the abundance of possessions.”
—Bible: New Testament, Luke 12:15.
“Slavery is founded in the selfishness of man’s nature—opposition to it, is [in?] his love of justice.... Repeal the Missouri compromise—repeal all compromises—repeal the declaration of independence—repeal all past history, you still can not repeal human nature. It still will be the abundance of man’s heart, that slavery extension is wrong; and out of the abundance of his heart, his mouth will continue to speak.”
—Abraham Lincoln (1809–1865)
“We do not want actions, but men; not a chemical drop of water, but rain; the spirit that sheds and showers actions, countless, endless actions.”
—Ralph Waldo Emerson (1803–1882)
“A party of order or stability, and a party of progress or reform, are both necessary elements of a healthy state of political life.”
—John Stuart Mill (1806–1873)