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absolute configuration

absolute configuration   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
573 words
Illustration(s):
1

A way of denoting the absolute structure of an optical isomer (see optical activity). Two conventions are in use: The ...

abstraction

abstraction   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
42 words
Illustration(s):
1

A chemical reaction that involves bimolecular removal of an atom or ion from a molecule. An example is the abstraction of hydrogen from methane by reaction with a radical:...

acenaphthene

acenaphthene   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
25 words
Illustration(s):
1

A colourless crystalline aromatic compound, C12H10; m.p. 95°C; b.p. 278°C. It is an intermediate in the production of some dyes....

acetals

acetals   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
120 words
Illustration(s):
1

Organic compounds formed by addition of alcohol molecules to aldehyde molecules. If one molecule of aldehyde (RCHO) reacts with one molecule of alcohol (R...

acetylcholine

acetylcholine   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
57 words
Illustration(s):
1
A substance that is released at some (cholinergic) nerve endings. Its function is to pass on a nerve impulse to the next nerve (i.e. at a synapse) or to initiate muscular contraction. Once ... More
acid

acid   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
621 words
Illustration(s):
8

1. A type of compound that contains hydrogen and dissociates in water to produce positive hydrogen ions. The reaction, for an acid HX, is commonly written:...

acid anhydrides

acid anhydrides   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
146 words
Illustration(s):
2

Compounds that react with water to form an acid. For example, carbon dioxide reacts with water to give carbonic acid:...

acidic hydrogen

acidic hydrogen   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
56 words
Illustration(s):
1

A hydrogen atom in an *acid that forms a positive ion when the acid dissociates. For instance, in methanoic acid ...

acridine

acridine   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
50 words
Illustration(s):
1
A colourless crystalline heterocyclic compound, C12H9N; m.p. 110°C. The ring structure is similar to that of anthracene, with three fused rings, the centre ring containing a nitrogen ... More
activation energy

activation energy   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
172 words
Illustration(s):
1
Symbol E a. The minimum energy required for a chemical reaction to take place. In a reaction, the reactant molecules come together and chemical bonds are stretched, broken, and ... More
activity

activity   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
230 words
Illustration(s):
5
1. Symbol a. A thermodynamic function used in place of concentration in equilibrium constants for reactions involving nonideal gases and solutions. For example, in a reaction ... More
acylation

acylation   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
61 words
Illustration(s):
1

The process of introducing an acyl group (RCO–) into a compound. The usual method is to react an alcohol with an acyl halide or a carboxylic acid anhydride; e.g....

adamantane

adamantane   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
27 words
Illustration(s):
1

A colourless crystalline hydrocarbon C10H16; m.p. 269°C. It is found in certain petroleum fractions. The structure contains three symmetrically fused cyclohexane rings....

addition reaction

addition reaction   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
100 words
Illustration(s):
1

A chemical reaction in which one molecule adds to another. Addition reactions occur with unsaturated compounds containing double or triple bonds, and may be ...

adenine

adenine   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
26 words
Illustration(s):
1

A *purine derivative. It is one of the major component bases of *nucleotides and the nucleic acids *...

adenosine

adenosine   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
35 words
Illustration(s):
1

A nucleoside comprising one adenine molecule linked to a d-ribose sugar molecule. The phosphate-ester derivatives of adenosine, AMP, ADP, and ...

adrenaline

adrenaline   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
54 words
Illustration(s):
1
A hormone, produced by the medulla of the adrenal glands, that increases heart activity, improves the power and prolongs the action of muscles, and increases the rate and depth of ... More
adsorption indicator

adsorption indicator   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
111 words
Illustration(s):
1

A type of indicator used in reactions that involve precipitation. The yellow dye fluorescein is a common example, used for the reaction ...

aflatoxin

aflatoxin   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
51 words
Illustration(s):
1
A poisonous compound, C15H12O6, produced by the fungus Aspergillus flavus. It is extremely toxic to farm animals and can cause liver cancer in humans. It may occur as a contaminant of ... More
alcohols

alcohols   Quick reference

A Dictionary of Chemistry (7 ed.)

Reference type:
Subject Reference
Current Version:
2016
Subject:
Science and technology, Chemistry
Length:
186 words
Illustration(s):
1

Organic compounds that contain the –OH group. In systematic chemical nomenclature alcohol names end in the suffix -ol. Examples are methanol, CH...

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