A Dictionary of
`Chemistry
`
`
`
`FIFTH EDITION
`
`Edited by
`JOHN DAINTITH
`
`OXFORD
`
`UNIVERSITY PRESS
`
`1
`
`|
`
`APPLE 1023
`
`APPLE 1023
`
`1
`
`

`

`OXFORD
`UNIVERSITY PRESS
`
`Great Clarendon Street, Oxford OX2 6DP
`
`Oxford University Press is a departmentofthe University of Oxford.
`It furthers the University’s objective ofexcellence in research, scholarship,
`and education by publishing worldwide in
`Oxford New York
`
`Auckland Bangkok Buenos Aires Cape Town Chennai
`Dar es Salaam Delhi Hong Kong Istanbul Karachi Kolkata
`Kuala Lumpur Madrid Melbourne Mexico City Mumbai Nairobi
`Sio Paulo Shanghai Singapore Taipei Tokyo Toronto
`
`Oxford is a registered trade mark of Oxford University Press
`in the UK and in certain other countries
`
`© Market House Books Ltd. 1985, 1990, 1996, 2000, 2004
`
`The moral rights of the author have been asserted
`
`Database right Oxford University Press (maker)
`
`First published 1985 as A Concise Dictionary ofChemistry
`Secondedition 1990
`Third edition 1996
`Fourth edition 2000
`Fifth edition 2004
`
`All rights reserved. No part of this publication may be reproduced,
`stored in a retrieval system, or transmitted in any form or by any means,
`.
`without the prior permission in writing of Oxford University Press,
`or as expressly permitted by law, or under terms agreed with the appropriate
`reprographics rights organization. Enquiries concerning re}
`outside the scope ofthe above should be sentto the Rights Department,
`Oxford University Press, at the address above
`
`You mustnotcirculate this book in any other binding or cover
`and you must impose this same condition on any acquirer
`
`British Library Cataloguing in Publication Data
`Data available
`
`Library ofCongress Cataloging in Publication Data
`Data available
`
`ISBN 0-19-860918-3
`
`1 T
`
`ypeset in Swift by Market House Books Ltd.
`
`Printed in Great Britain by Clays Ltd, St Ives pic
`
`2
`
`

`

`Planck constant
`
`444
`
`Tatio
`ue
`
`an)
`
`and
`
`becamea professor at Berlin University in 1892. Here he formula
`*quantum theory, which had its basis in a paper of 1900. One of a. the
`importantscientific discoveries of the century, this work earneg hin
`1918 Nobel Prize for physics.
`the
`Planck constant Symbol h. The fundamental constantequal to th
`of the energy of a quantum of energy to its frequency.It has the val
`6.626 0755(40) x 104 J s. It is named after Max Planck. In quantum.
`mechanicalcalculations the rationalized Planck constant (or Dirac const
`h = h/2n = 1.054589 x 10*J s is frequently used.
`plane-polarized light See polarization of light.
`plaster of Paris The hemihydrate of *calcium sulphate, 2CaSO,H,0
`prepared by heating the mineral gypsum. When groundtoafine powilen
`and mixed with water, plaster of Paris sets hard, forming interlocking
`crystals of gypsum. The setting results in an increase in volumeandso the
`plaster fits tightly into a mould.It is used in pottery making,as a cast for
`setting broken bones, and as a constituent of the plaster used in the
`building industry.
`plasticizer A substance added to a synthetic resin to makeit flexible. See
`plastics.
`plastics Materials that can be shaped by applying heat or pressure. Most
`plastics are made from polymeric synthetic *resins, although a few are
`based on natural substances(e.g. cellulose derivatives or shellac). They fall
`into two main classes. Thermoplastic materials can be repeatedly softened by
`heating and hardened again on cooling. Thermosetting materials areinitially
`-soft, but changeirreversibly to a hard rigid form on heating.Plastics
`contain the synthetic resin mixed with such additives as pigments,
`plasticizers (to improveflexibility), antioxidants and otherstabilizers,
`fillers. See Chronology.
`plastocyanin A blue copper-containing protein that is found in
`chloroplasts and acts as an electron carrier molecule in the light-dependen’
`reactions of *photosynthesis. Plastocyanin consists of amino acid groups °
`association with a copper molecule whichgives this compounda blue
`colour.
`ts, that functions 4s one of
`;
`plastoquinone A quinone, found in chloroplas
`hain in the light
`the carrier molecules of the electron transport c
`dependentreactions of *photosynthesis.
`platinum SymbolPt. A silvery white metallic *transitionelement (s
`platinum metals); a.n. 78; r.a.m. 195.09; r.d. 21.45, m.P. 1772°C; -ound
`3827+100°C. It occurs in some nickel and copper ores and is a “int
`native in some deposits. The main sourceis the anodesludge °tory
`copper-nickel refining. The elementis used in jewellery. is and in
`apparatus(e.g. thermocouples, electrodes,etc.), electrical Or
`enation
`certain alloys(e.g. with iridium or rhodium). It is also 4 hydrog
`
`;
`
`e also
`
`3
`
`

`

`
`
`
`
`
`
`
`
`
`WS
`pLastics
` 1851
`
`scottish chemist Charles Macintosh (1766-1843) ma
`kes ebonite (from
`rubber).
`British chemist Alexander Parkes (1813-90) patents Parkesi
`arKesine, a plastic
`made from nitrocellulose, methanol, and wood pulp;
`It is later called
`‘celluloid’.
`British chemist Charles Williams (1829-1910) Preparesisoprene(synthetic
`rubber).
`US printerJohn Hyatt (1837-1920) develops commercial process for
`making celluloid.
`French chemist Hilaire de Chardonnet (1839-1 924) develops process for
`making rayon.
`
`British chemists Edward Bevan (1856-1921) and Charles Cross
`(1855-1935) develop the viscose process for making rayon.
`
`British chemist Frederick Kipping (1863-1949)discoverssiliconeplastics.
`
`German chemists Krische and Spitteler make formaldehyde—casein plastic
`(Galalith).
`
`
`Belgian-born US chemist Leo Baekland (1863-1944)invents Bakelite.
`Swiss chemist Jacques Brandenberger produces Cellophane(viscose
`
`cellulose film).
`
`US Formica Insulation company markets plastic laminate made from
`formaldehyderesins.
`
`Hans John prepares urea—formaldehyderesin.
`German chemist Hermann Staudinger (1881-1965) discovers the
`
`polymeric nature ofplastics.
`-
`US chemist Waldo Semon develops PVC (polyviny! chloride).
`
`Canadian chemist William Chalmers discovers polymethylmethacrylate
`(Perspex andPlexiglass).
`
`
`German chemists at IG Farbenindustrie produce polystyrene.
`
`Wallace Carothers invents nylon.
`
`US chemist Roy Plunkett produces polytetrafluoroethene(PTFE).
`
`British companyICI develops commercial process for making polyethene.
`
`British chemists John Whinfield (1901-66) and J..Dickson develop Terylene
`
`acron),
`German CompanyIG Farbenindustrie produces polyurethane.
`
`US Dow Corning company producessilicone plastics. Fs
`
`British chemists produceacrylic fibres.
`bes
`|
`lyst for making
`herman chemist Karl Ziegler (1896-1973) discovers cata
`
`gh-density polyethene.
`ae
`
`Italian chemist Giulio Natta (1903-79) develops industrialprocess for
`
`making high-density polyethene(using Ziegler, catalyst).
`1989
`
`Htalian company Ferruzzi produces biodegradable plastic
`
`
`(based on starch),
`ne
`
`
`
`
`
`1859
`
`1860
`
`1868
`
`1884
`
`1892
`
`1899
`
`1901
`
`1905
`
`1912
`
`1913
`
`1918
`
`1926
`
`1930
`
`1930
`
`1930
`
`1931
`
`1938
`
`1939
`1944
`
`1944
`1943
`1947
`1953
`
`1954
`
`,
`
`4
`
`

`

`|—
`
`485
`
`retort
`
`0
`
`thetic or naturally occurring *polymer. Synthetic resins are
`;
`resin A syn
`*plastics. Natural resins are acidic chemicals secreted by
`ysed — (especially conifers) into ducts or canals. They are found either
`ttle glassy substances or dissolved in essential oils, Their
`functions are
`43s ae similar to those of gums and mucilages.
`jution The process of separating a racemic mixtureintoits optically
`reso constituents. In some cases the crystals of the two forms have a
`ea appearance, and the separation can be done by hand.In general,
`eret physical methods(distillation, crystallization,etc.) cannot be used
`cause the optical isomers have identical physical properties, The most
`»mmon techniqueis to react the mixture with a compoundthatis itself
`optically active, and then separate the two.For instance, a racemic mixture
`of LA and d-A reacted with LB, gives two compoundsAB thatare not
`optical isomers but diastereoisomers and can be separated and reconverted
`into the pure I-A and d-A. Biological techniques using bacteria that convert
`one form but not the other can also be used.
`resonance The representation of the structure of a molecule by two or
`more conventional formulae. For example, the formula of methanal can be
`represented by a covalent structure H,C=O,in which there is a double bond
`in the carbonyl group. It is known that in such compoundsthe oxygen has
`some negative charge and the carbon somepositive charge. The true
`bonding in the molecule is somewhere between H,C=O andtheionic
`compound H,C*O’.It is said to be a resonance hybrid of the two, indicated by
`H,C=O eo H,C’O™
`The two possible structures are called canonical forms, and they need not
`contribute equally to the actual form. Note that the double-headed arrow
`does not imply that the two formsare in equilibrium.
`resonance effect See electronic effects.
`resonance ionization spectroscopy (RIS) A spectroscopic techniquein
`which single atoms in a gas are detected using a laser to ionize that atom.
`A sample containing the atomsto be excited is subjected to light from a
`laser, tuned so that only that type of atom is excited by thelight. If the
`frequency of light at which the atom is excited is v, the atoms in the
`xcited state can be ionized if the ionization potential of the atom is less
`Saiteats- IN contrast to other techniques of ionization, this type of
`light Ben only occurs for atomsthat are ‘in tune’ with the frequency of
`a give -use RIS 1s very selective in determining which atom Is ionized for
`" *Tequency it has many applications in chemistry.
`resorcino| See 13-dihydroxybenzene.
`-
`retinol see Vitamin A.
`reneces Fn laboratory apparatus consisting of a glass bulbwith a long
`Processes vessel used for reaction or distillation in industrial chemical
`
`Cor:
`
`a
`
`5
`
`