Science / Chemistry Glossary

Alkane: A series of organic compounds with general formula CnH2n+2. Alkane names end with -ane. Examples are propane (with n=3) and octane (with n=8).

Alkene: A compound that consists of only carbon and hydrogen, that contains at least one carbon-carbon double bond. Alkene names end with -ene. Examples are ethylene (CH2=CH2); 1-propene (CH2=CH2CH3 . . . View Full Definition

Alkoxide: (RO- M+) alkoxide ion. An ionic compound formed by removal of hydrogen ions from the hydroxyl group in an alcohol using reactive metals, e. G. Sodium. For example, potassium metal reacts wit . . . View Full Definition

Alkyl: (-cnh2n+1) alkyl group. A molecular fragment derived from an alkane by dropping a hydrogen atom from the formula. Examples are methyl (CH3) and ethyl (CH2CH3).

Alkyl Halide: An alkyl group attached to a halogen atom.

Alkyne: A compound that consists of only carbon and hydrogen, that contains at least one carbon-carbon triple bond. Alkyne names end with -yne. Examples are acetylene (CHidentCH); 1-propyne (CH2iden . . . View Full Definition

Allo: A prefix that designates the more stable of a pair of geometric isomers. allo- is sometimes used less precisely to designate isomers or close relatives of a compound.

Allobar: A form of an element that has isotopic abundances that are different from the naturally occuring form. For example, 'depleted' uranium has had most of the uranium-235 removed, and is an allo . . . View Full Definition

Allomer: Allomerism. Substances with different chemical composition but the same crystalline form.

Allosteric Effect: allosteric interaction A change in the behavior of one part of a molecule caused by a change in another part of the molecule.

Allotrope: Some elements occur in several distinct forms called allotropes. Allotropes have different chemical and physical properties. For example, graphite and diamond are allotropes of carbon.

Alloy: A mixture containing mostly metals. For example, brass is an alloy of copper and zinc. Steel contains iron and other metals, but also carbon.

Allyl: A molecular fragment derived by removing a methyl hydrogen from propene (-CH2-CH2=CH2). For example, 'allyl chloride' is 3-chloropropene, Cl-CH2-CH2=CH2.

Alpha Particle: (42He) A particle that is commonly ejected from radioactive nuclei, consisting of two protons and two neutrons. Alpha particles are helium nuclei. Alpha particles have a mass of 6.644 655 98 . . . View Full Definition

Alpha Ray: (alpha-ray) alpha radiation A stream of alpha particles. Alpha rays rapidly dissipate their energy as they pass through materials, and are far less penetrating than beta particles and gamma rays.

Amalgam: An alloy that contains mercury.

American Chemical Society (Acs): A large and influential professional society for professionals and students in chemistry and related fields.

Amide: An amide is an organic compound that contains a carbonyl group bound to nitrogen: . The simplest amides are formamide (HCONH2) and acetamide (CH3CONH2).

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