CHEMICAL NOMENCLATURE FOR USE IN MATRICULATION
EXAMINATIONS
October 2003
MATRICULATION AND SECONDARY EDUCATION CERTIFICATE
EXAMINATIONS BOARD
Foreword
This document is intended as a guide for teachers, examiners and students preparing for
the Advanced (mainly) and Intermediate Matriculation Examinations in Chemistry of the
University of Malta. It deals with the nomenclature of those inorganic and organic
compounds likely to be relevant to the syllabus matter of these examinations. The
document is inspired especially by information contained in the publications listed in the
reference section: these books contain significantly longer “Lists of recommended
names” than found here.
The statements in this document must not be construed as extending, in any way, the
examinable material described in the Syllabus for Intermediate and Advanced Chemistry
of the Matriculation and Secondary Education Certificate Examinations Board.
The Syllabus Panel working on the review of the Advanced and Intermediate Chemistry
Syllabus for 2005-7 has approved this document.
Alfred J. Vella
Department of Chemistry
University of Malta
October 2003
© Matriculation and Secondary Education Certificate Examinations Board, 2003
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CHEMICAL NOMENCLATURE FOR USE IN MATRICULATION
EXAMINATIONS
1. Chemical nomenclature in Matriculation examination papers
It is proposed that the following principles are followed in setting examination questions
for Matriculation Chemistry.
(a) In general, recommended names derived from rules of nomenclature as outlined
in this publication are used for all compounds.
(b) In the case of carbon compounds and their derivatives, recommended names are
used except that common names may be used additionally for certain well-known
compounds, especially those containing one or two carbon atoms, monosubstituted benzene derivatives and natural products.
In answers to examination questions, candidates may use any name or symbol, which is
generally accepted for a compound or a group, unless the question is specifically on some
aspect of nomenclature that falls within the syllabus.
2. Inorganic Nomenclature
This section describes briefly some aspects of nomenclature as it pertains to those
inorganic compounds as may be encountered in the syllabus material for Matriculation
Chemistry; parts of this discussion are not applicable to Intermediate Chemistry.
Names for inorganic compounds can be trivial or systematic and the choice of name is
dictated by the context; e.g. the substance known trivially as Glauber’s salt can be named
systematically as sodium sulfate-10-water. Trivial names are generally sufficient to
identify what is in a bottle and, if for no other reason than this, will probably remain
indefinitely as part of school chemical knowledge.
2.1 Binary compounds
Binary compounds have names ending in ‘-ide’ with the more electropositive element
named first, e.g. ZnO is zinc oxide, OF2 is oxygen difluoride. For historical reasons,
hydroxides and cyanides break this rule. Other chief exceptions are water, ammonia
(which may, in future, be renamed ‘azane’), methane and other non-metal hydrides. A
Roman numeral in parenthesis indicates the oxidation number of the less electronegative
constituent after the name of that element unless the compound consists of simple
molecules whose composition is revealed by the name itself. For example, copper(I)
oxide, phosphorus(V) oxide but sulfur dioxide for SO2 and phosphorus trichloride for
PCl3.
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Notice the spelling ‘sulfur’ for the element S (rather than ‘sulphur’) and this accords with
IUPAC rules, although phosphorus retains its traditional spelling.
In ionic or polymeric solids, the oxidation state of the electropositive element is given
unless there can be no doubt about what it is, e.g. sodium chloride not sodium(I) chloride
but copper(II) bromide; for Ag+, the oxidation state may be omitted (even though a few
silver(II) compounds exist since these will almost certainly not be encountered in school
chemistry).
2.2 Simple salts
Simple salts are named as shown in the following illustrative examples: Al(NO3)3:
aluminium nitrate(V); KHCO3: potassium hydrogencarbonate; CuSO4: copper(II)
sulfate(VI); PbCO3: lead(II) carbonate; AgNO3: silver nitrate(V).
2.3 Double salts, basic salts and double oxides
In double salts there are two cations that are independent of each other, though each
might be hydrated, e.g. the alums; less commonly there may be more than one anion.
The order of naming is that cations precede anions and within each category the ions are
listed in alphabetical order of their names. In writing chemical formulae, however, the
sequence within each class should be in alphabetical order of the symbols except that
hydrogen is always cited last, before the anion.
Basic salts are named as double salts with oxide or hydroxide anions whenever the
structure is known and the same procedure is used for double oxides.
Examples:
aluminium potassium sulfate(VI)-12-water
ammonium chromium(III) sulfate(VI)-12-water
bismuth(III) chloride oxide
sodium hydrogensulfate(IV)
dilead(II) lead(IV) oxide
oxovanadium(IV) sulfate(VI)
AlK(SO4)2.12H2O
CrNH4(SO4)2.12H2O
BiClO
NaHSO3
Pb 3O4 or (PbII)2PbIVO4
VOSO4
2.4 Coordination compounds
Coordination compounds are treated as consisting of a central metal ion to which ligands
(ions or molecules) are attached to form a complex. As in simple ionic salts, for ionic
coordination compounds, the cation is named first and then the anion. The name of the
complex is formed by placing the names of the ligands in alphabetical order, ignoring
numerical prefixes, before the name of the central atom. The oxidation number of the
central atom is placed after the metal name for a complex cation and after the metal name
and the suffix ‘-ate’ for a complex anion. For some metals, the Latin version of the name
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is used in anionic complexes, the more important cases being ferrate for Fe, argentate for
Ag, stannate for Sn and plumbate for Pb. For the purposes of the Matriculation
Examination, in writing formulae of complexes containing more than one type of ligand,
the metal ion should always appear first but the ligands may be shown in any order.
Examples:
tetraamminecopper(II)
tetracarbonylnickel(0)
pentacyanonitrosylferrate(II)
hexaaquaaluminium(III)
tetraamminechloronitrocobalt(III) nitrate(V)
[Cu(NH3)4] 2+
Ni(CO)4
[Fe(CN)5(NO)]2[Al(H2O)6]3+
[Co(NH3)4(NO2)Cl]NO3
There is no hyphen between the numerical prefixes and the names of the ligands (e.g.
between ‘hexa’ and ‘ammine’ or ‘aqua’). Anionic ligands have names ending in ‘o’
derived by adding the letter to the stem name of the group, e.g. chloro for Cl-, cyano for
CN-, OH- hydroxo. For neutral ligands, the name of the free molecule is used as such but
special names are given to some common ligands, of which the more important are aqua
(H2O), ammine (NH3), carbonyl (CO) and nitrosyl (NO).
2.5 Hydrates
The number of water molecules of hydration are shown by an Arabic number after the
name of the anhydrous substance as shown by this example: copper(II) sulfate(VI)-5water. The formula is written thus: CuSO4.5H2O. If the context warrants, this salt may
also be described as tetraaquacopper(II) sulfate(VI)-1-water. When the extent of
hydration is unknown, or the context warrants it, the word “hydrated” may be placed
before the name of the anhydrous material.
2.6 Oxoacids
Oxoacids and their salts are named as ‘-ic acid’ and ‘-ate’, respectively, giving the
oxidation number of the central atom. The number of oxygen atoms need not be
indicated. Thus, although the name of the species SO42- is formally tetraoxosulfate(VI),
the species can also be named sulfate(VI) and the latter form will be used in examination
papers. In the traditional system, the use of the terms ‘sulfate’ and ‘sulfite’ distinguished
between the two oxoanions of sulfur, i.e. sulfate(VI) and sulfate(IV), and similarly the
use of the terms ‘nitrate’ and ‘nitrite’. Use of these names, and of the corresponding
acids (sulfuric, sulfurous, nitric and nitrous) will be allowed in the examination, but not
in answers to questions dealing specifically with nomenclature when students are
expected to give systematic names. The ion S2O32- will be named ‘thiosulfate’ without
reference to oxidation number (which raises problems).
Phosphorus oxoacids require special mention. The distinction between simple and
condensed acids and their salts is made by using names such as phosphate(V) for PO43-,
diphosphate(V) for P2O72-, (cf dichromate(VI)), implying presence of P-O-P link and
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polytrioxophosphate(V) for (PO3)nn-. Those acids containing P-H bonds are named as
follows:
HOPH2O
phosphinic acid
(HO)2PHO phosphonic acid
(previously hypophosphorous acid)
(previously phosphorous acid)
and the corresponding salts are phosphinate (PH2O2-) and phosphonate (PHO32-). The
terms hypophosphite and phosphite should not be used.
Although the free acid (HO)3P , or trioxophosphoric(III) acid is not known, esters
regarded as derived from it exist and are named as phosphate(III), e.g. (C2H5O)3P is
triethyl phosphate(III). These organophosphorus compounds, however, are not included
in the current Advanced Chemistry syllabus.
2.7 List of recommended names of typical inorganic species (with traditional names)
The following list, which is not comprehensive, is intended to illustrate further the
application of the rules of nomenclature as described in this document.
Recommended Name (and formula, where
appropriate)
aluminate ion, regarded as AlO2- or Al(OH)4ammonium dihydrogenphosphate(V)
ammonium iron(II) sulfate(VI)-6-water
ammonium peroxodisulfate(VI)
ammonium polytrioxovanadate(V),
NH4VO3
aqueous ammonia, NH3(aq)
aqueous calcium hydroxide
bromate(I), BrObromic(V) acid, HBrO3
carbon (diamond)
carbon (fullerene)
chlorate(III), ClO2chlorate(VII), ClO4dichlorine oxide
chromium(III)
hexacyanoferrate(II)
disulfate(IV), S2O52hydrazinium chloride
tetrahydridoaluminate
hydrogendifluoride ion, HF2iron(II) disulfide
dilead(II) lead(IV) oxide
manganate(VII)
nitric(III) acid
Traditional Name
aluminate ion
ammonium dihydrogenorthophosphate
ferrous ammonium sulphate
ammonium persulphate
ammonium vanadate
ammonium hydroxide
limewater
hypobromite
bromic acid
diamond
buckminsterfullerene
chlorite
perchlorate
chlorine monoxide
chromic
ferrocyanide
metabisulphite
hydrazine hydrochloride
aluminohydride
hydrogen fluoride ion
iron pyrites
triplumbic tetraoxide, red lead
permanganate
nitrous acid
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Recommended Name (and formula, where
appropriate)
nitryl cation, NO2+
oxoacids
ozonolysis
trioxygen (in discussing allotropy)
oxygen or dioxygen (in discussing
allotropy)
phosphorus(III) oxide
phosphorus trichloride oxide
phosphorus pentachloride, PCl5 (as gas, the
Traditional Name
nitronium ion
oxyacids
ozonolysis
ozone
oxygen
phosphorus trioxide
phosphorus oxychloride
phosphorus pentachloride
solid is, strictly, tetrachlorophosphonium(V)
hexachlorophosphate(V))
silicon(IV) oxide
disulfur dichloride
sulfur dichloride dioxide, SCl2O2
sulfur dichloride oxide, SCl2O
tetrahydridoaluminate ion, AlH4vanadium(IV) oxide sulfate, VOSO4
zincate ion (tetrahydroxozincate(II) and
silicon dioxide, silica
sulphur monochloride
sulphuryl chloride
thionyl chloride
aluminohydride ion
vanadyl sulphate
zincate ion
trihydroxozincate(II) may exist in aqueous solution
while molten sodium zincate may contain
dioxozincate(II) ions. Other solid zincates should be
named as double oxides.
3. Organic Nomenclature
3.1 General Principles
The IUPAC nomenclature is used: every name consists of a root, one suffix and as many
prefixes as necessary. For the purposes of the Advanced Chemistry syllabus, the root is
an aliphatic hydrocarbon or a single ring homocyclic system: multicyclic and
heterocyclic compounds are not in the syllabus.
Compounds are regarded as derived from hydrocarbons by replacement of hydrogen
atoms by alkyl or other groups and by introduction or saturation of multiple bonds. The
systematic name is formed by attaching a suffix and prefixes to denote this substitution of
hydrogen. While only one suffix may be used, as many prefixes as are needed may be
included. The following list of functional groups defines the priority order for the
principal group to be chosen as the suffix: the group nearest the top of the list has the
higher priority.
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Formula
Name as Suffix
Name as Prefix Name as Suffix
(if the functional group
carbon is not counted in
C-chain forming the root)
-COOH
-COO-COOR
-COCl
-CONH2
-CN
-CHO
-CO
-OH
-NH2
-oic acid
-oate (ion)
alkyl…-oate
-oyl halide
-amide
-nitrile
-al
-one
-ol
-amine
cyanooxooxohydroxyamino-
-carboxylic acid
-carboxylate (ion)
alkyl…-carboxylate
-carbonyl halide
-carboxamide
-carbonitrile
-carbaldehyde
In the carbon-containing functional groups given in the list, the carbon atom of the
functional group is counted in the carbon chain which forms the root. Any other group
present in a structure, including those not in the above list such as –Cl, and -NO2, is
named by a prefix. If more than one prefix is needed they are placed in alphabetical
order. Multiplying prefixes, such as di- or tri- do not affect alphabetical order. The
syllables ‘ane’, ‘ene’ and ‘yne’ for denoting alkane, alkene and alkyne functionality
respectively are regarded to form part of the root and not as suffixes. When ‘ene’ and
‘yne’ appear together in a name, they are included in alphabetical order.
For certain structures, it may be required to include carbon-containing functional groups
in the name of the compound by using a prefix (e.g. “chlorocarbonyl” for -COCl ):
questions involving the naming of such structural formulae will not be set in the
Matriculation Examination.
The carbon atoms in the parent hydrocarbon (the root) are numbered consecutively and
the appropriate number (locant) precedes the name of the prefix or suffix indicating the
group attached to that carbon atom. The numbering is arranged to give, first, the lowest
possible number to the group cited by a suffix and then the lowest possible individual
numbers (not sum!) to those groups cited as prefixes, observing that when series of
locants containing the same number of terms are compared term by term, that series is
“lowest” which contains the lowest number on the occasion of the first difference. This
principle is applied irrespective of the nature of the substituents. The lowest possible
locant is assigned to a C=C double bond when present.
Numbers are omitted when the structure can be deduced without them, especially the
locant ‘1’, e.g. butanone not butan-2-one.
An italicised atomic symbol is used in appropriate circumstances to indicate the atom to
which the substituent is attached, e.g. N-phenylpropanamide.
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Other illustrative examples:
ClCH2CH2Br
HOCH2CH2CH2CHO
CH3OC(CH3)3
HOCH2CH2NH2
CH3CH2CH(CH3)CH(CH3)(CH2)4CH(CH3)2
HC C CH2CH CHCH3
1-bromo-2-chloroethane
4-hydroxybutanal
2-methoxy-2-methylpropane
2-aminoethan-1-ol or 2-aminoethanol
2,7,8-trimethyldecane
hex-2-ene-5-yne
4-methylpent-2-ene
CH3CH=CHCH(CH3)2
3.2 Aromatic compounds
A Kekulé structure or a hexagon/circle symbol may be used for benzene. The benzene
ring is numbered from the carbon atom to which the principal group is attached. Students
are expected to be familiar with the nomenclature for disubstituted benzene rings which
in place of numeral locants uses the prefixes ortho-, meta- and para- (abbreviated o-, m-,
p-) e.g. p-nitrophenol for 4- nitrophenol; or o-dichlorobenzene for 1,2-dichlorobenzene.
Homologues of benzene are named as alkylbenzenes, e.g. ethylbenzene for C6H5CH2CH3.
When a side-chain contains a functional group it would be possible either to name the
compound as a derivative of benzene or to name it as a phenyl-substituted aliphatic
compound. The guiding principle is to use a name that places emphasis on the functional
group that dominates the chemistry being taught at school level. Thus while
C6H5CH=CH2 can either be named ethenylbenzene or phenylethene, it is recommended
to adopt the second name since at Advanced Matriculation Level, the substance is studied
as a substituted alkene. However, either name derived as explained earlier will be
acceptable to the examiners.
To name benzene rings substituted by carboxylic acids or derivatives, etc. the use of
suffixes -carboxylic acid, -carbaldehyde etc. is recommended, e.g. benzene-1,2dicarboxylic acid; benzenecarboxamide (C6H5CONH2); benzenecarbonyl chloride
(C6H5COCl). However, semi-systematic names for these compounds will also be
acceptable, e.g. benzamide for benzenecarboxamide, benzoyl chloride for
benzenecarbonyl chloride, 2-nitrobenzaldehyde for 2-nitrobenzenecarbaldehyde.
The names phenol and phenyl, derived from “phene”, an unsuccessful replacement name
for benzene, continue to be used but polyhydroxy-compounds of benzene should be
named systematically, e.g. benzene-1,4-diol but 4-nitrophenol and not 4-nitrohydroxybenzene.
3.3 Amines
At present amines are generally named as methylamine, phenylamine, diethylamine,
methylethylamine etc. However, for primary amines, alternatives derived from the name
of the alkane rather than the alkyl group, e.g. methanamine for methylamine, are also
acceptable and may be encountered in the examination paper. (N.B. Other examining
boards may not be happy with such names and prefer alkylamines.) When an amine
group is not bonded to the first carbon atom of an alkyl chain or when more than one
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amine group is present, a substitutive name such as propan-2-amine or ethane-1,2diamine, analogous to benzene-1,3-diamine, can be used.
Amine salts should be named as alkylammonium compounds, e.g. ethylammonium
chloride for C2H5NH3Cl; use of names such as “ethylamine hydrochloride” should be
avoided.
Use of the systematic name for ethylenediaminetetraacetic acid, which is 1,2bis[bis(carboxymethyl)amino]ethane is not recommended and will not be tested; rather
this compound should be referred to as “H4edta” since “edta” is the commonly used term
for the ligand formed from the parent acid by loss of protons. Similarly, use of the
abbreviation “en” for ethane-1,2-diamine in formulae showing this substance reacting as
a ligand is acceptable.
3.4 Terms and generic names
The following list contains some of the terms and generic names which continue to be
useful and may be encountered in examination questions.
Acetal; acetylide; alcohol; aldehyde; aliphatic; alkoxide; alkyl; amide; amine; amino acid;
anhydride; aromatic; aryl; carbohydrate; carbonyl; carboxyl; cyanohydrin; epoxide; ester;
ether; glycol; hemiacetal; hydroxy acid; ketone; monosaccharide; nitrile; peptide; phenol;
polymer; polysaccharide; protein; sugar; sulfonic acid.
The terms ‘primary, secondary, tertiary’ as applied to classes of alcohols and amines
remain useful; however prefixes such as n-, iso-, sec-, tert- etc are not recommended.
Thus iso-propyl becomes 1-methylethyl.
3.5 Polymers
Polymers are named according to one of two systems: either one that is based on the
source (monomer) or process from which the polymer is made or one based on the
structure of the polymer itself. Most addition polymers are named according to the
monomer or source from which they were formed while most condensation polymers are
described by the types of linkages involved in their structures.
The source-based naming of addition polymers leads to poly(alkene) descriptions, e.g.
poly(propene), poly(methyl 2-methylpropenoate) (for acrylic, Perspex or polymethyl
methacrylate). The structure based name for poly(tetrafluoroethene) would be
poly(difluoromethylene). It is recommended to use the source-based system of naming
for addition polymers.
Names for condensation polymers are difficult to construct and will not be tested. These
polymers should be described by simple block diagrams such as
…–NHCO-‫ٱ‬-CONH-X-NHCO-‫ٱ‬-CONH-X-NHCO-…
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The latter structure could represent a polyamide such as, e.g., Nylon-6,6 derived from
condensation of a six-carbon diamine (hexane-1,6-diamine) and a six-carbon diacid
(hexanedioic acid).
3.6 Policy on dual naming
Much chemical information is currently available in sources using many trivial or semisystematic names and this situation will probably continue long into the future. It is thus
felt that the commoner of the traditional names should be taught alongside the systematic
names and these names should include formic, acetic, benzoic and their related names,
ethylene, acetylene and phenol. This knowledge, however, will not be examined unless
in a manner that does not raise any doubt; moreover, the use of these names in student
answers will be permitted unless given in response to questions on nomenclature, when
systematic or, for aromatic compounds, semi-systematic names will be expected. Thus 2nitrobenzenecarboxylic acid and 2-nitrobenzoic acid are equally acceptable names and
both may be employed in the examination paper. In biochemistry, trivial names and
approved abbreviations (e.g. Ala, Gly) for amino acids should continue to be employed
when the structure of the entity is not being considered. It is strongly recommended that
optical activity in molecules be represented by the symbols + and – and use of the letters
d and l be discontinued.
3.7 List of recommended names of typical organic species (with traditional names)
The following list, which is not comprehensive, is intended to illustrate further the
application of the rules of nomenclature as described in this document.
Recommended Name
alkanes
alkanoic acids
alkenes
alkyl
alkylmagnesium halide
alkynes
aminoethanoic acid
arenes
aryl
benzenecarbaldehyde or
benzaldehyde
benzenecarbaldehyde oxime or
benzaldehyde oxime
benzenecarbonitrile or
benzonitrile
benzenecarbonyl chloride or
benzoyl chloride
Traditional Name
paraffins
fatty acids
olefins
alkyl
alkyl magnesium halide (Grignard reagent)
acetylenes
glycine
aromatic hydrocarbons
aryl
benzaldehyde
benzaldoxime
benzonitrile
benzoyl chloride
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Recommended Name
benzenediazonium ion
benzenesulfonic acid
but-1-ene
cis-butenedioic acid
trans-butenedioic acid
calcium ethynediide or
calcium dicarbide
carbamide or urea
1,2,3,4,5,6-hexachlorocyclohexane
trichloromethane
(chloromethyl)benzene
chloro-2-methylbenzene
(trichloromethyl)benzene
dicopper(I) ethynediide
ethanenitrile
ethanal oxime
ethanal tetramer
ethanal trimer
ethane-1,2-diol
ethanoic anhydride
ethanoic methanoic anhydride
ethenyl ethanoate
ethoxyethane
ethyl benzenecarboxylate or ethyl benzoate
cyclohexene
4-hydroxy-4-methylpentan-2-one
2-hydroxy-2-methylpropanenitrile
2-hydroxypropane-1,2,3-tricarboxylic acid
litmus
methyl orange
2-methylbenzenecarboxylic acid or
2-methylbenzoic acid
3-methylbutyl1,1-dimethylethyl2-methyl-1,3,5-trinitrobenzene
N-methylphenylamine
4-nitrophenylamine
3-oxobutanoic acid
pentylbenzeneperoxycarboxylic acid or
peroxybenzoic acid
phenol
phenylamine
4-(phenylazo)phenol
Traditional Name
benzenediazonium or phenyldiazonium ion
benzenesulphonic acid
butylenes
maleic acid
fumaric acid
calcium carbide or calcium acetylide
urea
benzene hexachloride
chloroform
benzyl chloride
o-chlorotoluene
benzotrichloride
cuprous acetylide
acetonitrile
acetaldoxime or acetaldehyde oxime
metaldehyde
paraldehyde
ethylene glycol
acetic anhydride
acetic formic anhydride
vinyl acetate
ether or diethyl ether
ethyl benzoate
cyclohexene
diacetone alcohol
acetone cyanohydrin
citric acid
litmus
methyl orange
o-toluic acid
isoamyltert-butyltrinitrotoluene
N-methylaniline
p-nitroaniline
acetoacetic acid (keto form)
n-amyl
perbenzoic acid
phenol
aniline
p-hydroxyazobenzene
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Recommended Name
phenylmethanol
(phenylmethyl)amine
diphenylmethanone
poly(tetrafluoroethene)
propane-1,2,3-triol
propane-1,2,3-triyl trinitrate(V)
sodium ethoxide
sodium phenoxide
Traditional Name
benzyl alcohol
benzyl amine
benzophenone
poly(tetrafluoroethylene) or ptfe
glycerol or glycerine
glyceryl trinitrate or nitroglycerine
sodium ethoxide or sodium ethylate
sodium phenoxide or sodium phenate
4. References
Chemical nomenclature, symbols and terminology for use in school science, 3rd Edition,
The Association for Science Education, 1985.
Swinfen, T.C., Signs, symbols and systematics, The ASE companion to 16-19 science,
The Association for Science Education, 2000.
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