Dictionary of Chemistry [6th Ed.]
groups 3–12 See transition el- ements. group 13 elements A group of el- ements in the *periodic table: boron (B), aluminium (Al) ...
IV, which consisted of two sub- groups: IVB (the main group) and group IVA. Group IVA consisted of ti- tanium (Ti), zirconium (Z ...
Ülled inner levels. They are also called the chalcogens. Formerly, they were classiÜed in group VI, which consisted of two subgr ...
GSC(gas–solid chromatography) See gas chromatography. G-seriesSee nerve agents. guanidine A crystalline basic com- pound HN:C(NH ...
H Haber, Fritz (1868–1934) German chemist who worked at the Karl- sruhe Technical Institute, where he perfected the *Haber proce ...
a cofactor or prosthetic group to form the haemoproteins. These are haemoglobin, myoglobin, and the cytochromes. Essentially, ha ...
Dirk Coster (1889–1950) and George de Hevesey (1885–1966) in 1923. A Information from the WebElements site Hahn, Otto(1879–1968 ...
1914), who discovered it indepen- dently in the same year. hallucinogen A drug or chemical that causes alterations in perception ...
halogen. This occurs with alkanes, where the reaction involves free radi- cals and requires high temperature, ultraviolet radiat ...
Only iodine, however, forms positive ions, as in I+NO 3 –. halonA compound obtained by re- placing the hydrogen atoms of a hy- d ...
5- membered rings have olefor un- saturated and olanefor saturated compounds. Rules are given for nam- ing compounds with two or ...
ecules or crystal lattices at low tem- peratures can be regarded as good ap- proximations to harmonic oscillators in quantum mec ...
h.c.p.Hexagonal close packing. See close packing. headspaceThe space above a sam- ple held in a sealed container. Head- space an ...
101.4°C. Deuterium oxide, D 2 O, oc- curs to a small extent (about 0.003% by weight) in natural water, from which it can be sepa ...
Helmholtz modelSee electrical double layer. hemeSee haem. hemiacetalsSee acetals. hemicelluloseA *polysaccharide found in the ce ...
fold axis as a special case.) As regards the cubic groups, Ohis denoted m 3 m (or 4/m 3 _ 2/m), O is denoted 432, This denoted m ...
227 °C. It is made by the chlorination of benzene with an iron(III) chloride catalyst or by treating hexachlorocy- clohexane wit ...
are the two *frontier orbitals of the molecule. high frequency (HF)A radio fre- quency in the range 3–30 megahertz; i.e. having ...
rocket propellant. The name comes from ‘High Molecular Weight RDX’. HNIW(hexanitrohexaazaisowurtzi- tane)A powerful explosive, C ...
(C 2 H 5 COOH), etc., form a homolo- gous series in which each member differs from the next by CH 2. Succes- sive members of suc ...
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