All articles starting with R

Radical (chemistry)

A radical, often called a free radical or chemical radical, is a molecular entity with an unpaired electron, typically highly reactive and driving polymerization, atmospheric oxidation, and biological signaling.

Radical 1,2-metalate rearrangement

The radical 1,2-metalate rearrangement is a reaction in which an organic radical combines with a boron ate complex, causing a carbon substituent to migrate and form a new carbon-carbon bond.

Radical addition

Radical addition is an organic reaction in which a free radical adds to an unsaturated molecule such as an alkene, forming a new sigma bond and a new radical.

Radical alkylation

Radical alkylation is the formation of a carbon–carbon bond by adding a carbon-centered alkyl radical to a substrate, most often electron-deficient heteroarenes such as pyridines and pyrimidines.

Radical borylation

Radical borylation forms carbon–boron bonds through radical intermediates, typically via metal-free photochemical, electrochemical, or thermal activation of alkyl halides, carboxylic acid derivatives, and C–H bonds for late-stage functionalization.

Oct 15, 2026

Radical center (geometry)

The radical center, also called the power center, of three circles is the point where the three pairwise radical axes meet, existing whenever the circle centers are not collinear.

Radical centrism

Radical centrism, also known as the radical center or radical middle, is a political stance pursuing far-reaching structural reform by drawing on ideas from both left and right.

Radical Chic & Mau-Mauing the Flak Catchers

Radical Chic & Mau-Mauing the Flak Catchers is a 1970 book of two Tom Wolfe essays, including "Radical Chic," about a Bernstein Black Panther fundraiser.

Sep 24, 2026

Radical Civic Union

The Radical Civic Union (Unión Cívica Radical) is an Argentine political party founded in 1891 to fight electoral fraud, governing under Yrigoyen and Alvear from 1916 to 1930.

Radical conjugate addition

Radical conjugate addition is a carbon-carbon bond-forming reaction in which a carbon-centered radical adds to the β-carbon of an electron-deficient alkene; the intermolecular version is known as the Giese reaction.

Radical copolymerization

Radical copolymerization is a copolymerization reaction in which two or more monomers join a growing chain by free-radical means, supplying about 45% of manufactured plastics worldwide.

Radical cyclization

Radical cyclization is an organic reaction in which a radical intermediate adds to a multiple bond within the same molecule, forming a ring used to build carbocycles and heterocycles.

Radical cystoprostatectomy

Radical cystoprostatectomy is an operation removing the bladder and prostate together with the seminal vesicles, vas deferens, and pelvic lymph nodes, performed to treat bladder cancer.

Radical Dreamers

Radical Dreamers – Le Trésor Interdit – (ラジカル・ドリーマーズ) is a 1996 Japan-only Satellaview text adventure bridging Chrono Trigger and Chrono Cross, starring Serge, Kid, and Magil, first released in the West in the 2022 Chrono Cross remaster.

Radical Entertainment

Radical Entertainment, Vancouver studio founded 1991 by Armes, Davis, and Wilkinson; maker of The Simpsons: Hit & Run, Hulk: Ultimate Destruction, and Prototype; Vivendi 2005, Activision 2008, gutted 2012; revived 2026 as New Radical Games.

Radical feminism

Radical feminism, also called radfem, is a second-wave feminist tendency identifying patriarchy as the root of women's oppression and seeking fundamental social restructuring; it arose from the 1960s women's liberation movement and popularized "the personal is political."

Radical hydroamination

Radical hydroamination is the addition of an amine across a carbon–carbon double or triple bond via radical intermediates, prized for anti-Markovnikov addition to unactivated alkenes that polar catalysis handles poorly.

Radical hydrofunctionalization

Metalloradical hydrogen atom transfer hydrofunctionalization, usually called MHAT, is a family of alkene reactions in which a cobalt, manganese, or iron hydride transfers a hydrogen atom to form a radical and a new bond.

Radical hysterectomy

Radical hysterectomy is a surgical operation that removes the uterus, parametrium, and upper one-third to one-half of the vagina, usually with pelvic lymph node dissection, to treat early-stage cervical cancer.

Radical mastectomy

The radical (Halsted) mastectomy is an operation for breast cancer removing the breast, both pectoral muscles, and all axillary lymph nodes, devised by William Halsted in 1894.

Radical methylation

Radical methylation is the attachment of a methyl group via radical intermediates rather than polar SN2 transfer, used by radical SAM enzymes and synthetic chemists.

Radical neck dissection

Radical neck dissection is an operation for head and neck cancer removing neck lymph nodes plus the internal jugular vein, sternocleidomastoid muscle, and spinal accessory nerve.

Radical nephrectomy

Radical nephrectomy is a urologic operation that removes an entire kidney, with its surrounding fat within Gerota's fascia, to treat renal cell carcinoma, reserved for larger or more complex tumors.

Radical of an ideal

The radical of an ideal I in a commutative ring, written √I, is the set of elements some positive power of which lies in I; it is itself an ideal containing I.

Radical Optimism

Radical Optimism is Dua Lipa's third studio album, released 3 May 2024 on Warner Records; a psychedelic electro-pop record with Kevin Parker and Danny L Harle that debuted at UK Number 1. Distinct from the philosophical term and Bruteau's 1993 book of the same name.

Radical Optimism Tour

Radical Optimism Tour: Dua Lipa's third headlining world tour (2024–2025), supporting her album Radical Optimism; 81 shows across five continents, opening in Asia in November 2024, with Wembley Stadium dates and TAIT-built staging.

Oct 15, 2026

Radical pair mechanism

The radical pair mechanism is a physical process in which a weak magnetic field like Earth's alters chemical reactions involving radical pairs, proposed to underlie birds' magnetic compass.

Radical Party (France)

Radical Party (Parti radical, formerly Parti républicain, radical et radical-socialiste; Parti radical valoisien 1974), France's oldest active political party, founded June 1901; anticlerical center-left dominant force of the Third and Fourth Republics, later centered.

Radical Party (Italy)

Radical Party (Partito Radicale), Italian liberal party founded December 1955 by the PLI left wing and Amici del Mondo; led by Marco Pannella and Emma Bonino, it won the 1974 divorce referendum, peaked at 3.4% in 1979, and became a transnational party in 1988-89.