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Chemical similarity (or molecular similarity) refers to the similarity of chemical elements, molecules or chemical compounds with respect to either structural or functional qualities, i.e. the effect that the chemical compound has on reaction partners in inorganic or biological settings.
Diamond and graphite are two allotropes of carbon: pure forms of the same element that differ in crystalline structure.. Allotropy or allotropism (from Ancient Greek ἄλλος (allos) 'other' and τρόπος (tropos) 'manner, form') is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of the elements.
[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 ...
The compound chlorofluoromethane, in contrast, is not chiral: the mirror image of its molecule is also obtained by a half-turn about a suitable axis. Another example of a chiral compound is 2,3-pentadiene H 3 C − CH = C = CH − CH 3 {\displaystyle {\ce {H3C-CH=C=CH-CH3}}} a hydrocarbon that contains two overlapping double bonds.
Carbon is capable of forming many allotropes (structurally different forms of the same element) due to its valency (tetravalent). Well-known forms of carbon include diamond and graphite. In recent decades, many more allotropes have been discovered and researched, including ball shapes such as buckminsterfullerene and sheets such as graphene.
While the term chemical substance is a precise technical term that is synonymous with chemical for chemists, the word chemical is used in general usage to refer to both (pure) chemical substances and mixtures (often called compounds), [14] and especially when produced or purified in a laboratory or an industrial process.
When different elements undergo chemical reactions, atoms are rearranged into new compounds held together by chemical bonds. Only a few elements, such as silver and gold, are found uncombined as relatively pure native element minerals. Nearly all other naturally occurring elements occur in the Earth as compounds or mixtures.
The following are subcategories containing chemical compounds by element. An alternative listing of inorganic compounds may be found at inorganic compounds by element . Wikimedia Commons has media related to Chemical compounds by element .