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Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
A synthetic element is one of 24 known chemical elements that do not occur naturally on Earth: they have been created by human manipulation of fundamental particles in a nuclear reactor, a particle accelerator, or the explosion of an atomic bomb; thus, they are called "synthetic", "artificial", or "man-made".
The metal, or various compounds, can be toxic to humans. [13] In plants, aluminum can be the primary limitation on growth in acidic soils. [14] antimony: 51: 2c: Has no known biological role, but has a variety of uses in medicine, e.g. antibacterial. [15] Some compounds are highly toxic to humans. [11] argon: 18: 2: None known. [11] None known ...
In a biochemistry that used sulfuric acid as a solvent, the alkene group (C=C), with two carbon atoms joined by a double bond, could function analogously to the carbonyl group (C=O) in water-based biochemistry. [43] A proposal has been made that life on Mars may exist and be using a mixture of water and hydrogen peroxide as its solvent. [79]
The 5-membered ring compounds containing two heteroatoms, at least one of which is nitrogen, are collectively called the azoles. Thiazoles and isothiazoles contain a sulfur and a nitrogen atom in the ring. Dithioles have two sulfur atoms. A large group of 5-membered ring compounds with three or more heteroatoms also exists.
[16] [17] [18] A molecule may be homonuclear, that is, it consists of atoms of one chemical element, as with two atoms in the oxygen molecule (O 2); or it may be heteronuclear, a chemical compound composed of more than one element, as with water (two hydrogen atoms and one oxygen atom; H 2 O). A molecule is the smallest unit of a substance that ...
A heme-containing group of enzymes: Cytochrome P450; Porphyrin coordinated to magnesium: chlorophyll; The one-carbon-shorter analogues: corroles, including vitamin B 12, which is coordinated to a cobalt; Corphins, the highly reduced porphyrin coordinated to nickel that binds the Cofactor F430 active site in methyl coenzyme M reductase (MCR)
Ionic bonding is a type of chemical bond that involves the electrostatic attraction between oppositely charged ions, and is the primary interaction occurring in ionic compounds. The ions are atoms that have lost one or more electrons (termed cations) and atoms that have gained one or more electrons (termed anions). [23]