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isomer

(Encyclopedia)isomer īˈsəmər [key], in chemistry, one of two or more compounds having the same molecular formula but different structures (arrangements of atoms in the molecule). Isomerism is the occurrence of ...

formyl group

(Encyclopedia)formyl group fôrˈmĭl [key], in chemistry, functional group that consists of a carbonyl group joined by a single bond to a hydrogen atom. Aldehydes are compounds that contain a formyl group joined b...

hydroxyl group

(Encyclopedia)hydroxyl group hīdrŏkˈsĭl [key], in chemistry, functional group that consists of an oxygen atom joined by a single bond to a hydrogen atom. An alcohol is formed when a hydroxyl group is joined by ...

Sabin, Joseph

(Encyclopedia)Sabin, Joseph săbˈĭn [key], 1821–81, American bibliophile, b. England. Sabin came to the United States in 1848 and established himself as a dealer in rare books in New York City and Philadelphia....

chemical bond

(Encyclopedia)chemical bond, mechanism whereby atoms combine to form molecules. There is a chemical bond between two atoms or groups of atoms when the forces acting between them are strong enough to lead to the for...

mass number

(Encyclopedia)mass number, often represented by the symbol A, the total number of nucleons (neutrons and protons) in the nucleus of an atom. All atoms of a chemical element have the same atomic number (number of pr...

fatty acid

(Encyclopedia)fatty acid, any of the organic carboxylic acids present in fats and oils as esters of glycerol. Molecular weights of fatty acids vary over a wide range. The carbon skeleton of any fatty acid is unbran...

Novoselov, Sir Konstantin Sergeevich

(Encyclopedia)Novoselov, Sir Konstantin Sergeevich, 1974–, Russian-British physicist, Ph.D. Univ. of Nijmegen, Netherlands, 2004. He has been a research associate at the Univ. of Manchester, England, since 2001. ...

formula, in chemistry

(Encyclopedia)formula, in chemistry, an expression showing the chemical composition of a compound. Formulas of compounds are used in writing the equations (see chemical equations) that represent chemical reactions....

Geim, Sir Andre Konstantinovich

(Encyclopedia)Geim, Sir Andre Konstantinovich, 1958–, Russian-born Dutch physicist, Ph.D. Russian Academy of Sciences, 1987. He was a professor at the Univ. of Nijmegen in the Netherlands from 1994 to 2001, when ...