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The abundance of the chemical elements is a measure of the occurrences of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by mass fraction (in commercial contexts often called weight fraction), by mole fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases), or by volume fraction.
The abundance of elements in Earth's crust is shown in tabulated form with the estimated crustal abundance for each chemical element shown as mg/kg, or parts per million (ppm) by mass (10,000 ppm = 1%).
Regardless of significant differences between abundances of several elements in urban soils and those values calculated for the Earth's crust, the element abundances in urban soils generally reflect those in the Earth's crust. With the development of technology the abundances may be refined. Mass fraction, in mg/kg (ppm).
Oxygen gas is the second most common component of the Earth's atmosphere, taking up 20.8% of its volume and 23.1% of its mass (some 10 15 tonnes). [ 19 ] [ 70 ] [ d ] Earth is unusual among the planets of the Solar System in having such a high concentration of oxygen gas in its atmosphere: Mars (with 0.1% O
Carbonaceous asteroids are rich in CHON elements. [5] These asteroids are the most common type and frequently collide with Earth as meteorites. Such collisions were especially common early in Earth's history, and these impactors may have been crucial in the formation of the planet's oceans. [6]
The rarest elements in the crust (shown in yellow) are not the heaviest, but are rather the siderophile (iron-loving) elements in the Goldschmidt classification of elements. These have been depleted by being relocated deeper into Earth's core. Their abundance in meteoroid materials is higher. Additionally, tellurium and selenium have been ...
Magnesium and calcium are very common in the Earth's crust, being respectively the fifth and eighth most abundant elements. None of the alkaline earth metals are found in their elemental state. Common magnesium-containing minerals are carnallite, magnesite, and dolomite. Common calcium-containing minerals are chalk, limestone, gypsum, and ...
As such, iron is the most abundant element in the core of red giants, and is the most abundant metal in iron meteorites and in the dense metal cores of planets such as Earth. [29] It is also very common in the universe, relative to other stable metals of approximately the same atomic weight. [29] [30] Iron is the sixth most abundant element in ...