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radical,in chemistry, group of atoms that are joined together in some particular spatial structure and that take part in most chemical reactions as a single unit. Important inorganic radicals include ammonium, NH4; carbonate, CO3 ; chlorate, ClO3, and perchlorate, ClO4 ; cyanide, CN; hydroxide, OH; nitrate, NO3; phosphate, PO4; silicate, SiO3 (meta) or SiO4 (ortho); and sulfate, SO4. The use of these radicals simplifies the naming and description of inorganic compounds, since such usage does not consider the electronic charge on the group. (When ionsion,
atom or group of atoms having a net electric charge. Positive and Negative Electric Charges
A neutral atom or group of atoms becomes an ion by gaining or losing one or more electrons or protons.
..... Click the link for more information. are dealt with, electronic charge must be considered.) In organic chemistry, the term radical is sometimes used synonymously with group; e.g., the group CH3 is sometimes called the methyl radical instead of the methyl group. This use is limited chiefly to alkyl groupsalkyl group
, in chemistry, group of carbon and hydrogen atoms derived from an alkane molecule by removing one hydrogen atom (see radical). The name of the alkyl group is derived from the name of its alkane by replacing the -ane suffix with -yl, e.g.
..... Click the link for more information. and aryl groupsaryl group
, in chemistry, group of atoms derived from benzene or from a benzene derivative by removing one hydrogen that is bonded to the benzene ring (see radical). The simplest aryl group is phenyl, C6H5 ; it is derived from benzene.
..... Click the link for more information. ; it is usually not applied to functional groupsfunctional group,
in organic chemistry, group of atoms within a molecule that is responsible for certain properties of the molecule and reactions in which it takes part. Organic compounds are frequently classified according to the functional group or groups they contain.
..... Click the link for more information. , such as carbonyl. Because the term radical easily could be taken to mean a free radicalfree radical,
in chemistry, a molecule or atom that contains an unpaired electron but is neither positively nor negatively charged. Free radicals are usually highly reactive and unstable. They are produced by homolytic cleavage of a covalent bond (see chemical bond); i.e.
..... Click the link for more information. , the term group is preferred by some.
radical,in mathematics, symbol (√) placed over a number or expression, called the radicand, to indicate a rootroot,
in mathematics, number or quantity r for which an equation f(r)=0 holds true, where f is some function. If f is a polynomial, r is called a root of f; for example, r=3 and r
..... Click the link for more information. of the radicand. When used without a sign or index number, as in √4, it designates the positive square root of the radicand, i.e., 2. If both square roots are meant, the radical sign is preceded by ±, as in ±√4. To indicate higher roots of the radicand, e.g., cube or fourth roots, an index number is used, as in ∛27. The radical sign is generally taken to indicate the principal root of the radicand, i.e., ∛27 = 3, although any radicand will have n different nth roots. The term radical is sometimes used loosely to refer to the entire expression consisting of radical sign and radicand.
Radical(religion, spiritualism, and occult)
Radical is an adjective form of the noun radix, as in the “radical” position of the planets, meaning their original position in a horoscope chart.
(1) In capitalist countries, a member of a political party that demands in its program bourgeois-democratic reforms within the framework of the existing system.
(2) One who advocates a radical solution to problems.