heinemann chemistry 2 units 3 & 4 glossary

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absorbance The proportion of incident electromagnetic radiation absorbed by the sample.absorption tower A reaction vessel in the contact process in which sulfur trioxide is converted into oleum.absorption spectrum A plot of the proportion of electromagnetic radiation absorbed by a substance over a range of

wavelengths (or frequencies).accumulator A secondary or rechargeable electrochemical cell.acetylsalicylic acid An analgesic commonly known as aspirin.acid A substance that donates hydrogen ions (protons).acid rain Rainwater that has reacted with acidic emissions from industry and has a pH less than 5.5.acid–base indicator A substance whose colour depends on the concentration of H3O

+ ions in solution. Indicators are weak acids and bases; their acid form is one colour and their conjugate base is another.

acid–base reaction A reaction involving the transfer of a hydrogen ion (proton) from an acid to a base.acidic oxide An oxide that either reacts with water to form an acid or reacts with hydroxide ions.acidic solution Aqueous solution in which [H3O

+] > [OH–]. At 25°C, pH < 7.

acidity The concentration of H3O+ ions in an aqueous solution. Acidity is measured using the pH scale.

acidity constant An equilibrium constant, Ka, which measures the degree of ionisation, or strength, of an acid.activation energy The energy required by reactants for reaction to occur. This energy is needed to break the bonds between

atoms in the reactants to allow products to form.active site� 7KH�ORFDWLRQ�RQ�DQ�HQ]\PH¶V�VXUIDFH�DW�ZKLFK�UHDFWLRQ�RFFXUV��,W�LV�XVXDOO\�D�ÀH[LEOH�KROORZ�RU�FDYLW\�LQ�WKH�PROHFXOH�addition polymerisation Reaction of a large number of unsaturated monomers to form a polymer that has the same empirical

formula as the monomers.addition reaction A reaction in which a molecule binds to an unsaturated hydrocarbon, forming a single carbon-to-carbon bond.

In this process two reactant molecules become one.adenine A base found in nucleic acids such as DNA. It is the complementary base of thymine.adsorption The attraction of one substance to the surface of another.alcohol An organic compound containing the hydroxyl functional group, e.g. ethanol (CH3CH2OH).aliquot A volume of liquid measured by a pipette.alkaline cell A commercial electrochemical cell with an alkaline electrolyte that is a moist paste rather than a solution. An organic

compound that has the carboxyl functional group attached to an alkane chain, e.g. CH3COOH0.alkanes Hydrocarbons with only single bonds between carbon atoms, which have the general formula C

nH2n + 2.

alkanoic acid Systematic name for a carboxylic acid. An organic compound that has the carboxyl functional group attached to an alkane chain, e.g. CH3COOH.

alkanol Systematic name for an alcohol. An organic compound that has the hydroxyl functional group attached to an alkane chain, e.g. ethanol, CH3CH2OH.

alkenes Hydrocarbons with one double bond between carbon atoms, which have the general formula CnH2n

.alkyl group A group obtained by removing a hydrogen atom from an alkane, with general formula C

nH2n + 1, e.g. methyl (CH3).

alkyne Hydrocarbon with one triple bond between carbon atoms, which have the general formula CnH2n – 2.

alternative reaction pathway A product may be formed by more than one reaction pathway. Each alternative pathway involves a different sequence of intermediate reactions, each having a different activation energy.

amide A compound containing the CONH functional group. This group forms the link between amino acids in proteins. See peptide linkage.

amine An organic molecule containing the NH2 functional group.amino acid A molecule that contains both an amino group and a carboxy group.!-amino acid An amino acid that has its amino, carboxy and Z groups attached to one central carbon atom. Also known as a

2-amino acid.2-amino acid See !-amino acid.amount of substance A measure used by chemists for counting particles; the unit is the mole.amphoteric oxide An oxide that can act as an acid or a base.analgesic A drug that relieves pain.anhydrous An anhydrous solid does not contain water molecules in its lattice structure.

Glossary


annealing The stage in the polymerase chain reaction (PCR) where primers form hydrogen bonds to their complementary base sequences at the end of a DNA strand.

anode An electrode at which an oxidation reaction occurs.anodising An electrolytic process that increases the thickness of the oxide layer on aluminium, making it harder and more

corrosion resistant.antibiotic A chemical used to treat infectious disease in humans and animals.arenes Cyclic (ring-shaped) molecules in which electrons are delocalised around the ring, e.g. benzene.aspirin� $�FRPPRQ�GUXJ�XVHG�WR�WUHDW�SDLQ��IHYHU�DQG�LQÀDPPDWLRQ��DQG�WR�UHGXFH�EORRG�FORWWLQJ��$OVR�NQRZQ�D�DFHW\OVDOLF\OLF�DFLG�atomic absorption spectroscopy (AAS) An analytical technique that uses light absorption to measure the concentration of a

metal in a sample.atomic emission spectrometry (AES) An analytical technique that uses light emission to measure the concentration and

identity of a metal in a sample.atomic number Number of protons in the nucleus of an atom.average (mean) titre The value to use in calculating the result of a volumetric analysis. Found by taking the average of three

concordant titres.Avogadro’s number The number of particles in a mole; symbol NA. NA = 6.022 × 1023.

B100 100% biodiesel fuel.back titration A technique used when an acid or base is too weak to be analysed by direct titration. The process involves adding

an excess of a strong base or acid to the original substance and then determining, by titration, how much of the added chemical remains unreacted.

base A substance that accepts hydrogen ions (protons).base pairs Pairs of complementary bases found in DNA, i.e. (i) adenine (A) and thymine (T), or (ii) cytosine (C) and guanine (G).base peak The highest intensity peak in a mass spectrum; it is assigned an intensity of 100%.basic solution A solution where [H3O

+] < [OH–]. At 25°C, pH > 7.basic oxide An oxide of a metal which either reacts with water to form hydroxide ions or reacts with H3O

+ ions.batch processing� $�PHWKRG�RI�SHUIRUPLQJ�UHDFWLRQV�LQ�ZKLFK�¿[HG�DPRXQWV�RI�UHDFWDQWV�DUH�PL[HG��JLYLQJ�¿[HG�DPRXQWV�RI�

products.battery A combination of cells connected in series.beamlines Instrumentation in the synchrotron that transports the photon beam from the source and selects the wavelength of

radiation emitted.benzene ring A six-carbon ring, C6H6, containing delocalised electrons. Forms compounds by replacing hydrogens with

functional groups.bioaccumulative Describes the tendency of a substance to increase in concentration as it moves through a food chain.biochemical fuel (biofuel) A fuel produced from biomass, i.e. from a plant or animal source or from micro-organisms.biodegradable Able to be broken down by biological processes.biodiesel A biochemical fuel made from vegetable oils or animal fats that can be used in place of diesel from petroleum.

Biodiesel molecules contain the ester functional group so are also known as bioesters.biofuel A fuel derived from plant, animal or microbial material, e.g. bioethanol, biodiesel. Biofuels are considered to be renewable

energy resources.biogas Combustible gas that is produced from the decay of organic matter in the absence of oxygen.biomass The mass of living matter in a population of organisms.black coal A fuel made from fossilised primitive plant material, with a higher carbon content than brown coal.brown coal A fuel made from fossilised primitive plant material with a carbon content between that of peat and black coal.bubble caps &DSV�¿WWHG�LQ�WKH�KRUL]RQWDO�WUD\V�RI�D�FUXGH�RLO�IUDFWLRQDWLQJ�WRZHU�WR�LPSHGH�WKH�ÀRZ�RI�JDVHV�WKURXJK�WKH�WRZHU��

giving better separation of hydrocarbons.buffer A solution composed of a weak acid and its conjugate base that resists changes of pH.burette An item of volumetric equipment that delivers variable volumes of solution accurately.button cell A small galvanic cell used in watches, cameras, calculators etc.by-product A substance that is produced at the same time as an intended product in the course of a chemical reaction.

calibration factor A measure of the amount of energy required to raise the temperature of a calorimeter and its contents by 1°C.calibration graph A plot of data involving two variables that is used to determine values for one of the variables.


calorimeter An instrument designed to measure energy changes in a reaction.carbohydrate A naturally occurring condensation polymer containing carbon, hydrogen and oxygen that has the

general formula Cx(H2O)

y.

carbon-13 NMR Nuclear magnetic resonance utilising the interaction of the 13&�QXFOHXV�ZLWK�DQ�H[WHUQDO�PDJQHWLF�¿HOG�DQG�electromagnetic radiation. Used to determine the chemical environment of carbon atoms in compounds.

carboxyl (or carboxy) group The functional group COOH.carboxylic acid An organic molecule containing the carboxyl functional group, e.g. ethanoic acid (CH3COOH).carrier gas The gas used as the mobile phase in gas chromatography.catalyst A substance that increases the rate of a reaction but is not consumed in the reaction.catalytic cracking The production of small hydrocarbon molecules by heating and breaking down larger hydrocarbons in the

presence of a catalyst.cathode An electrode at which a reduction reaction occurs.cellulose A carbohydrate found in the cell walls of plants. It is a polysaccharide formed by a condensation reaction of glucose.chain reaction A self-sustaining reaction involving a rapid series of steps initiated by a single reaction step.chemical analysis� ,GHQWL¿FDWLRQ�RI�WKH�FKHPLFDOV�SUHVHQW�LQ�D�VXEVWDQFH�RU�WKH�PHDVXUHPHQW�RI�WKHLU�FRQFHQWUDWLRQ�chemical energy The sum of the chemical potential energy and molecular kinetic energy in a substance.chemical equilibrium The point in a chemical reaction when the rate of the forward reaction equals the rate of the back

reaction.chemical shift Frequency of the signal in the NMR spectrum, relative to the TMS standard.chloro group The Cl functional group.chloroalkane A molecule derived from an alkane, containing a Cl functional group.cholesterol A lipid found in animals that is involved in the synthesis of a number of hormones. High levels of cholesterol are

linked to cardiovascular disease.chromatogram The trace or plot that is obtained when the components of a mixture are separated by chromatography.chromatography A technique for separating the components of a mixture. The components are carried by a mobile phase (gas

or liquid) over the adsorbent surface of a stationary phase, which can be solid or liquid.chromosome Threadlike strand of DNA, found in the nucleus of most cells.coagulation Clumping of denatured protein molecules to form a suspension.cofactor A small non-protein part of an enzyme which is essential for its ability to act as a catalyst.collision theory A theoretical model that accounts for the rate of chemical reactions in terms of collisions between particles

during a chemical reaction.colorimeter An instrument that enables the determination of the concentration of a coloured solution by measuring the amount of

light passing through a sample.colorimetry An analytical technique that uses the amount of light of a particular wavelength absorbed by a sample to determine

concentration.column chromatography A chromatographic technique in which the stationary phase is contained in a column, as for example

in gas chromatography.combined techniques A combination of two or more analytical techniques in the same instrument, e.g. gas chromatography–

mass spectrometry.combustion Rapid reaction with oxygen accompanied by the release of large amounts of heat; burning.competing equilibria Equilibria that have a common reactant; each equilibrium can be regarded as competing for this reactant.

7KH�HTXLOLEULXP�ZLWK�WKH�ODUJHU�HTXLOLEULXP�FRQVWDQW�KDV�D�VLJQL¿FDQW�HIIHFW�RQ�WKH�SRVLWLRQ�RI�HTXLOLEULXP�RI�WKH�RWKHU�reaction.

complementary base pairing The formation of hydrogen bonds between the base pairs adenine (A) and thymine (T), or cytosine (C) and guanine (G), in the two strands of the DNA double helix.

complementary colour When a substance absorbs a particular energy from white light, it appears coloured. The colour that is observed is not the same as the colour of the light absorbed. The two colours are said to be complementary.

complementary proteins Proteins that in combination provide the essential amino acids that are required for a healthy diet.concentration A measure of how much solute is dissolved in a unit quantity of solution.concentration fraction The ratio of concentrations of reactants and products, as expressed in the equilibrium law for a reaction.

The concentration fraction is also known as the reaction quotient.concordant titres 7LWUHV�WKDW�YDU\�ZLWKLQ�QDUURZO\�VSHFL¿HG�OLPLWV�condensation polymerisation Formation of a polymer by condensation reactions.condensation reaction A reaction in which two molecules link together, eliminating a small molecule such as water.


FRQLFDO�ÀDVN� $�ÀDVN�ZLWK�D�EURDG�EDVH�DQG�QDUURZ�QHFN��XVHG�LQ�WLWUDWLRQV�conjugate acid The conjugate acid of a base contains one more hydrogen ion (proton) than the base.conjugate acid–base pair An acid and its conjugate base.conjugate base The conjugate base of an acid contains one less hydrogen ion (proton) than the acid.conjugate redox pair An oxidant and its corresponding reduced form, e.g. Cu2+/Cu.contact process An industrial process used to manufacture sulfuric acid.FRQWLQXRXV�ÀRZ�SURFHVVLQJ A method of performing reactions in which reactants are mixed continuously to provide a constant

supply of products.converter A vessel in which reaction occurs in an industrial process.copolymer A polymer formed from more than one monomer.coulomb The unit of charge; symbol C.cracking The breaking of carbon-to-carbon bonds in hydrocarbons to form smaller molecules, some of which are unsaturated.culture Medium for growing bacteria.current� 7KH�ÀRZ�RI�FKDUJHG�SDUWLFOHV�WKURXJK�D�FRQGXFWRU��V\PERO�I. The unit of current is the ampere, A.cyclic molecule A ring-shaped molecule.cytosine A base found in nucleic acids such as DNA. It is the complementary base of guanine.

dangerous goods Materials that are potentially harmful to people, property or the environment.dehydrating agent A substance that removes water from other substances.denaturation A change to the structure and shape of a protein that prevents it from functioning.deoxyribose $�¿YH�FDUERQ�VXJDU�WKDW�LV�D�FRQVWLWXHQW�RI�'1$�deoxyribonucleic acid (DNA) A nucleic acid that carries genetic information in the cells of plants and animals. Each strand is

formed by a condensation polymerisation reaction between nucleotide monomers. Hydrogen bonds between complementary bases shape pairs of DNA molecules into a double helix structure.

desorption The breaking of the bonds between a substance and the surface to which the substance is adsorbed.desulfurisation� 7KH�UHPRYDO�RI�VXOIXU�FRPSRXQGV�IURP�SHWUROHXP�GXULQJ�UH¿QLQJ�diesel A fuel consisting of hydrocarbon molecules of chain length C13 to C25.dilution The addition of solvent to make a solution less concentrated.dipolar ion A particle carrying both a positive and negative charge, e.g. +H3NCH2COO–.dipole moment A measure of the strength and direction of charge separation in a molecule.diprotic acid Substance capable of donating two hydrogen ions.disaccharide A carbohydrate made from a condensation reaction between two monosaccharide molecules.discharge reaction The spontaneous reaction that occurs in an electrochemical cell, during which chemical energy is converted

into electrical energy.GLVXO¿GH�OLQN� $�ERQG�EHWZHHQ�WZR�VXOIXU�DWRPV�WKDW�IRUPV�D�OLQN�EHWZHHQ�GLIIHUHQW�SDUWV�RI�D�SURWHLQ�FKDLQ��LQÀXHQFLQJ�WKH�

tertiary structure of the protein.DNA database $�FROOHFWLRQ�RI�'1$�¿QJHUSULQWV�RU�SUR¿OHV�IURP�D�ODUJH�JURXS�RI�LQGLYLGXDOV�LQ�D�SDUWLFXODU�SRSXODWLRQ'1$�SUR¿OH� A series of bands formed by DNA fragments of different length, uniquely identifying an individual. Also referred to as

'1$�¿QJHUSULQW�double absorption A step in the contact process for the manufacture of sulfuric acid in which unreacted gases are recycled into

the converter to prevent the release of harmful emissions.double helix The secondary structure of DNA, in which the two strands wind around each other.Downs cell A commercial electrolytic cell that is used to produce sodium and chlorine.drug A substance that affects how the body functions.dry cell A commercial electrochemical cell with an electrolyte that is a moist paste rather than a solution.dynamic equilibrium A point in a chemical reaction when the rate of the forward reaction is equal to the rate of the back

reaction.

E10 A fuel consisting of 10% ethanol and 90% petrol.electrochemical cell A device that converts chemical energy into electrical energy.electrochemical series A list of chemical species arranged in order of their strength as oxidants.electrode A solid conductor in a half cell at which oxidation or reduction reactions occur.


electrolysis The production of a non-spontaneous redox reaction by the passage of electrical energy from a power supply through a conducting liquid.

electrolyte A solution that contains ions that are free to move and so conduct electricity.electrolytic cell A cell in which electrolysis can occur.electromagnetic spectrum All possible frequencies of electromagnetic radiation shown in wavelength order.electronegativity A measure of the electron-attracting power of an element.electronic energy levels� 'H¿QLWH�¿[HG�HQHUJLHV�WKDW�HOHFWURQV�LQ�DQ�DWRP�RU�PROHFXOH�FDQ�WDNH�electrophoresis� 7KH�SURFHVV�XVLQJ�DQ�HOHFWULF�¿HOG�WR�VHSDUDWH�'1$�IUDJPHQWV�RU�SURWHLQV�RQ�WKH�EDVLV�RI�WKHLU�VL]H�DQG�FKDUJH�electroplating The use of electrolysis to deposit a layer of metal on the surface of another material.element Matter containing atoms of the same atomic number.elongation Addition of complementary base pairs to a single strand of DNA.eluent A liquid used as the mobile phase in chromatography.emf Electromotive force; a measure of the energy given to electrons in a circuit.emission spectrum A display of the wavelengths of light emitted by a substance. For many metals this appears as coloured

lines on a black background.empirical formula The formula of a compound that indicates the simplest ratio of atoms of each element in the compound.end point The point during a titration when the indicator changes colour.endothermic An endothermic reaction is one in which the chemical energy of the reactants is less than that of the products

("H > 0).energy conservation� 7KH�UHGXFHG�RU�PRUH�HI¿FLHQW�XVH�RI�HQHUJ\�UHVRXUFHV�energy converter A device that changes energy from one form to another.energy density Amount of energy per unit mass or unit volume.HQHUJ\�SUR¿OH A graphical representation of the energy changes occurring during a chemical reaction.HQHUJ\�WUDQVIHU�HI¿FLHQF\ The percentage of energy transformed to its required form.enthalpy Heat content, symbol H; the sum of the chemical potential and molecular kinetic energies in the substance.environmental effects statement A decision-making tool that documents the environmental impact of a proposed development

project and typically involves consultation between community, government and corporate stakeholders.enzyme A protein molecule that acts as a catalyst for reactions in living things.equilibrium constant The value of K in the equilibrium law.equilibrium law The equilibrium law for the chemical equation aW + bX # cY + dZ is given by the expression

K = [Y]c[Z]d/[W]a[X]b, where K is a constant.equilibrium position The relative amounts of reactants and products in a reaction at equilibrium.equivalence point A point during a titration when the solutions have been mixed in the mole ratio shown by the reaction

equation.essential amino acids Nine amino acids that cannot be manufactured by the human body and are required for protein

formation. They must be provided directly from food.ester An organic compound containing the ester functional group –COO–.HVWHUL¿FDWLRQ�UHDFWLRQ The chemical reaction between an alcohol (alkanol) and a carboxylic (alkanoic) acid to form an ester as

the main product.ethanol A two-carbon member of the alkanol homologous series; found in alcoholic drinks.ether linkage A functional group that consists of an oxygen linking two hydrocarbons or sugars.excess reactant A reagent that is not completely consumed in a reaction.excited electrons Electrons that have absorbed particular quantities of energy and moved from their ground states to higher

energy levels.excited state The state of an atom, ion, etc. in which one or more electrons, nuclei or bonds have absorbed energy and are not

in their lowest energy levels.exothermic An exothermic reaction is one in which the chemical energy of the reactants is greater than that of the products

("H < 0).extent of reaction The relative amounts of products compared with reactants. The extent of a reaction is indicated by the value

of the equilibrium constant.external circuit The section of an electrochemical cell circuit in which electrons move, e.g. wires.


faraday The charge on one mole of electrons, symbol F.)DUDGD\¶V�¿UVW�ODZ�RI�HOHFWURO\VLV The mass of any substance deposited, evolved or dissolved at an electrode in an

electrochemical process is directly proportional to the quantity of electricity passed through the cell.Faraday’s second law of electrolysis For one mole of a substance to be deposited, evolved or dissolved at an electrode, the

passage of one, two, three or another whole number of moles of electrons is required.fats A nutrient group composed of triglyceride molecules formed from the reaction of glycerol and fatty acids. The term ‘fats’ may

be used to describe triglycerides that are solids, rather than liquids, at room temperature.fatty acid A carboxylic acid composed of molecules with long hydrocarbon chains.feedstock The raw materials that are introduced (fed) into an industrial chemical process.fermentation The breakdown of sugar solutions, by the action of enzymes in yeasts, into ethanol and carbon dioxide.¿QJHUSULQW� In chemical analysis, a spectrum or analysis that is unique to a particular chemical.ÀDPH�LRQLVDWLRQ�GHWHFWRU A device used to identify organic compounds leaving a GC column. The compounds are burnt in a

K\GURJHQ±R[\JHQ�ÀDPH�DQG�DUH�DWWUDFWHG�WR�HOHFWURGHV��FUHDWLQJ�DQ�HOHFWULF�FXUUHQW�formulation The particular form in which a drug is administered, e.g. as tablets, as an injection, etc.fossil fuels Coal, oil and natural gas; fuels derived from prehistoric plant and animal matter.fraction A group of molecules with similar boiling temperatures, separated from a mixture by fractional distillation.fractional distillation The separation of the components in a mixture on the basis of their boiling temperatures.fractionating tower $�WRZHU�XVHG�LQ�RLO�UH¿QLQJ�WR�VHSDUDWH�RLO�LQWR�LWV�IUDFWLRQV�fragmentation The break-up of a molecule into a number of different smaller fragments in a mass spectrometer, the mass of

which can be used to identify the molecule.free radicals An atom or group of atoms with at least one unpaired electron; this tends to make them highly reactive.frequency ($) The number of complete waves passing a particular point per second.fuel cell An electrochemical cell in which the reactants are supplied continuously, allowing continuous production of electrical

energy.functional group Atoms or groups of atoms in an organic molecule that largely determine the molecule’s properties and

reactions.

galvanic cell An electrochemical cell; a device that converts chemical energy into electrical energy.gas chromatography (GC) A form of chromatography in which the mobile phase is a gas. It includes the techniques of gas–

liquid chromatography and gas–solid chromatography.gas chromatography–mass spectrometry (GC-MS) A combined analytical technique in which the mass spectrometer

replaces the conventional detector in the gas chromatograph.gas–liquid chromatography (GLC) A very sensitive form of chromatography that is limited to separating compounds that can

be vaporised readily without decomposing. It uses an inert gas as the mobile phase and a viscous liquid as the stationary phase.

gas–solid chromatography (GSC) A chromatographic technique in which the mobile phase is a gas and the stationary phase an adsorbent solid such as alumina or activated charcoal.

gene A segment of DNA that provides the code for a polypeptide.general gas constant The constant, R, in the general gas equation (R = 8.31 J mol–1 K–1).general gas equation The equation that describes the behaviour of a gas: pV = nRT.genetic code The way in which the nucleotide sequence of DNA provides information for the production of proteins.genetic engineering The deliberate alteration of part of the DNA of an organism so as to introduce desired characteristics.genome All of the genetic information carried on the DNA of an individual a particular species.geothermal power A form of power generation using steam or hot water coming from within the Earth’s interior.glycerol An alcohol containing three OH groups. A glycerol molecule can react with three molecules of fatty acids to form a fat

molecule.glycogen A carbohydrate that is a means of storing glucose in animals.glycosidic (ether) linkage A C–O–C link formed when two monosaccharides combine to form a disaccharide.gravimetric analysis A type of analysis that involves precipitation and weighing.green chemistry Chemical technology to minimise or eliminate hazardous substances in the design, manufacture or use of

chemical products.greenhouse effect An effect involving absorption of infrared radiation by gases such as carbon dioxide and water vapour in the

atmosphere, which results in the trapping of heat by the Earth’s atmosphere.ground state A term used to describe atoms in which the electrons or nuclei are in their lowest possible energy levels.


guanine A base found in nucleic acids such as DNA. It is the complementary base of cytosine.

Haber process The industrial process used to manufacture ammonia from nitrogen and hydrogen.half cell Half an electrochemical cell containing an oxidant and the conjugate reductant. When two half cells are combined a

galvanic cell is formed.half equation An equation involving either an oxidation or a reduction process. The electrons lost or gained in this process are

shown in the equation.Hall–Héroult cell An electrolytic cell used for the industrial production of aluminium.hazardous substance A substance with the potential to harm the health or safety of people.HAZCHEM A code for identifying hazardous chemicals. Used in storage and transport of hazardous materials.heat content Chemical energy, symbol H; the sum of the chemical potential energy and molecular kinetic energy in a substance.heat exchangers Devices used to transfer heat from a substance to either its surroundings or another substance.heat of combustion� 7KH�HQHUJ\�UHOHDVHG�ZKHQ�D�VSHFL¿HG�DPRXQW��J��/��PRO��RI�D�VXEVWDQFH�EXUQV�FRPSOHWHO\�LQ�R[\JHQ�heat of reaction ("H) The energy released or absorbed during a chemical reaction.heating to constant mass The technique of repeatedly heating a sample to 100°C until the same mass is recorded on

successive weighings, to ensure that all water has been removed.heterogeneous catalysts Catalysts that are in a different state from the reactants.high performance (or pressure) liquid chromatography (HPLC) A very sensitive form of chromatography in which the

mobile solvent phase is pumped through the stationary phase under high pressure.high performance liquid chromatography–mass spectrometry (HPLC-MS) A combined analytical technique in which the

PDVV�VSHFWURPHWHU�UHSODFHV�WKH�FRQYHQWLRQDO�GHWHFWRU�LQ�+3/&�high temperature incineration The incineration of materials, typically above temperatures of 1100°C.histone A type of protein. DNA wraps around histones to form chromosomes.homogeneous catalysts Catalysts that are in the same state as the reactants.homologous series Organic compounds with the same functional groups in which each member of the groups differs from the

previous member by CH2.hydroelectricity� (OHFWULFLW\�JHQHUDWHG�E\�WKH�ÀRZ�RI�ZDWHU�WKURXJK�WXUELQHV�hydrogen bonds A strong dipole–dipole attraction that forms between molecules when hydrogen is bonded to one of the

HOHFWURQHJDWLYH�HOHPHQWV�R[\JHQ��QLWURJHQ�RU�ÀXRULQH�hydrolysis A reaction in which water is a reactant.hydroxyl group The OH functional group.

indicator A substance that has different colours in acidic and basic solutions.infrared spectroscopy An analytical technique that uses the infrared part of the electromagnetic spectrum.injection port The part of an analytical instrument into which a sample is injected.insulin A hormone that regulates the level of glucose in the body. This small protein is composed of 51 amino acids.internal circuit The part of an electrochemical cell in which ions move, e.g. solutions and salt bridge.ion–dipole bonding Attraction between an ion and a dipolar molecule.ionic equation An equation that contains only the ions that are involved in the reaction.ionisation constant of water The equilibrium constant Kw, where Kw = [H3O

+][OH–]. At 25°C, Kw = 1.0 × 10–14 M2.ionise Form a ion.isomers See structural isomers.

joule The unit of energy, symbol J.

law of conservation of energy When one form of energy is transformed, the total amount of energy remains unchanged.law of conservation of mass During a chemical reaction the total mass of the reactants is equal to the total mass of the

products.Le Chatelier’s principle If an equilibrium system is subjected to a change, the system will adjust itself to partially oppose the

effect of the change.lead–acid battery A secondary cell or accumulator used to start most cars.limiting reactant The reagent that is completely consumed in a reaction and which determines the amounts of products formed.lipids A class of nutrients made up of naturally occurring fats and oils that are esters of fatty acids.


liquid stationary phase A viscous liquid used as the stationary phase in chromatography. The components of a mixture undergo adsorption to this liquid as they are carried along by the mobile phase.

lithium ion cell A galvanic cell that generates electricity from the oxidation of lithium embedded in the lattice structure of a graphite rod and the reduction of a metal oxide, the reduction product combining with the lithium ions.

mass spectrometer An instrument designed to measure the mass-to-charge ratio of particles.mass spectrometry (MS) An analytical technique that uses the mass-to-charge ratio of atoms, molecules and fragments of

molecules to identify substances.mass spectrum A graph of data produced from a mass spectrometer indicating the abundance of each particle and the mass-to-

charge ratio.Material Safety Data Sheet (MSDS) Documented description of a substance that includes its identity, chemical and physical

properties, health hazard information, uses, precautions for use, disposal and safe handling information.membrane cell An electrolytic cell, used to produce sodium hydroxide, hydrogen and chlorine, that has a special plastic

membrane to prevent the mixing of products.mitochondrial DNA Non-nuclear DNA found in mitochondria, the energy-producing part of a cell.mobile phase The phase that moves over the stationary phase in chromatography.molar mass The mass of one mole of a substance, symbol M. It is equal to the relative mass of the substance expressed in

grams.molar volume of a gas The volume occupied by one mole of gas at a particular pressure and temperature; symbol Vm. At

VWDQGDUG�ODERUDWRU\�FRQGLWLRQV��WKH�PRODU�YROXPH�RI�D�JDV�LV�DSSUR[LPDWHO\��/�PRO–1; at standard temperature and SUHVVXUH�LW�LV��/�PRO–1.

molarity The amount of solute (mole) dissolved in one litre of solution.mole The amount of substance that contains the same number of fundamental particles as there are atoms in 12 g of 12

6C; symbol n.

molecular formula A formula that indicates the actual numbers and kinds of atoms in a molecule.molecular ions A molecule with either more or fewer electrons than it has protons so it carries an overall charge; in mass

spectrometry, the ions formed when electrons are knocked out of a molecule or molecule fragment.monochromator A device that selects a narrow range of wavelengths of light from a light source.monomers Small molecules that are able to react to form long chains of repeating units, called polymers.monoprotic An acid which is able to donate only one hydrogen ion.monosaccharide The simplest type of carbohydrate; formula C6H12O6.mono-unsaturated fat A fat made from fatty acids that contains only one carbon-to-carbon double bond.

natural gas Hydrocarbons that are gases under the conditions they are extracted from the Earth.neutral In a neutral solution, [H3O

+] = [OH–]. At 25°C, pH = 7.neutralisation The reaction of an acid with a base to form a salt and water.neutron A neutral particle found in the nucleus of an atom.nickel–cadmium cell A rechargeable cell that generates an electric current by the oxidation of cadmium and the reduction

of NiOOH.nickel–metal hydride cell A rechargeable cell that generates an electric current by the oxidation of nickel metal hydride and the

reduction of NiOOH.QLWURJHQ�¿[DWLRQ The conversion of atmospheric nitrogen into soluble nitrogen compounds that can be used by plants.nitrogenase� $Q�HQ]\PH�WKDW�FDWDO\VHV�WKH�¿[DWLRQ�RI�QLWURJHQ�non-rechargeable cell A primary electrochemical cell.non-renewable Non-renewable energy sources are those that are being used at a rate faster than they can be replaced.non-spontaneous reaction Reactions that would not normally occur without the application of electrical energy.QRQ�VWHURLGDO�DQWL�LQÀDPPDWRU\�GUXJV��16$,'V� A type of pharmaceutical that acts as a mild, non-addictive analgesic

(pain killer).QXFOHDU�¿VVLRQ A nuclear reaction involving the splitting of the nucleus of an atom and the formation of smaller nuclei.nuclear fusion A nuclear reaction where two small nuclei join together to form a larger nucleus.nuclear magnetic resonance (NMR) spectroscopy A technique used to analyse materials using the interaction of the

nucleus of particular atoms, usually 1H or 13&��ZLWK�DQ�H[WHUQDO�PDJQHWLF�¿HOG�DQG�HOHFWURPDJQHWLF�UDGLDWLRQ�nuclear shielding� 0RGL¿FDWLRQ�RI�WKH�HIIHFW�RQ�DQ�DWRP�RI�DQ�H[WHUQDO�PDJQHWLF�¿HOG�E\�WKH�PDJQHWLF�¿HOG�RI�VXUURXQGLQJ�

electrons.


nucleons The protons and neutrons in the nucleus of an atom.nucleotides The monomers of DNA, consisting of a phosphate group, deoxyribose sugar and a base (adenine, cytosine,

guanine or thymine) bonded together.nucleus The centre of an atom, which contains most of the mass of the atom and around which electrons move.

occupational health and safety Workplace practices to ensure employee safety.oil A mixture of hydrocarbons that is used as a source of chemicals and fuel. The term ‘oil’ is also used for a triglyceride that is a

liquid at room temperature.RLO¿HOG A site where crude oil is extracted from the Earth.oleum The compound H2S2O7 that forms when sulfur trioxide reacts with sulfuric acid.origin The point at which a small spot of a mixture is placed so that it can be separated by thin-layer chromatography.Ostwald process The industrial process used to manufacture nitric acid.oxidant A substance that causes another substance to be oxidised; in the process the oxidant is reduced.oxidation The loss of electrons by a chemical in a reaction.oxidation number� 1XPEHUV�WKDW�DUH�DVVLJQHG�WR�HOHPHQWV�WR�GHWHUPLQH�LI�D�UHDFWLRQ�FDQ�EH�FODVVL¿HG�DV�D�UHGR[�UHDFWLRQ��

Although they have no physical meaning, the numbers are assigned on the basis of a set of rules assuming that all molecular compounds are composed of ions.

oxidation state See oxidation number.oxidising agent An oxidant.oxidising strength The ability of a substance to accept electrons and so oxidise another.

parent molecular ion The ion formed when one electron is knocked out of a molecule in a mass spectrometer.peat A fuel made from prehistoric plant material; it has a lower carbon content than brown coal.penicillin A group of anti-bacterial drugs developed from moulds and which all contain a particular structural unit.peptide linkage The CONH functional group between amino acid units in polypeptides and proteins. Also called an amide group.percentage hydrolysis A measure of how readily a substance reacts with water.percentage ionisation A measure of how readily a substance undergoes an ionisation reaction.persistent pesticide A chemical that is used to kill insects and that does not break down rapidly.petrochemical A chemical derived from natural gas and crude oil.petrochemical industry Industries that use crude oil and natural gas to produce other chemicals.petroleum A mixture of hydrocarbons found underground.pH A measure of acidity; pH = –log10[H3O

+].pH curve A plot showing change in pH during a volumetric titration.phosphate group A phosphorus atom bonded to four oxygen atoms that is also bonded to deoxyribose in DNA.photon A ‘packet’ of energy that has a particular wavelength. A light beam is made up of photons.photosynthesis The conversion by green plants of carbon dioxide and water, in the presence of sunlight and chlorophyll, to

glucose and oxygen.pipette� $Q�LWHP�RI�YROXPHWULF�HTXLSPHQW�XVHG�WR�GHOLYHU�¿[HG�YROXPHV�RI�OLTXLG�DFFXUDWHO\�plasma A state of matter composed of electrons and bare nuclei that occurs at temperatures above 10 000°C.polar bond A covalent bond in which the electrons are not shared equally between the two atoms.polyester A condensation polymer formed from the reaction of certain carboxylic acids and alcohols.polymer A long-chain molecule that is formed by the reaction of large numbers of repeating units (monomers).polymerase chain reaction (PCR) A technique for making millions of copies of a segment of a DNA molecule.polynucleotide A polymer made from nucleotides, i.e. DNA or RNA.polypeptide A molecule made from amino acids.polyprotic acid An acid that can donate more than one hydrogen ion.polysaccharides Carbohydrates formed by a condensation reaction involving monosaccharide molecules.polyunsaturated fat A fat made from fatty acids that contain more than one carbon-to-carbon double bond.potential difference The emf, or ‘electrical pressure’, between two points in a circuit, such as the electrodes of an

electrochemical cell.precipitate A solid formed during a reaction in which two or more solutions are mixed.primary cell A galvanic cell that is non-rechargeable because the products of the reaction migrate away from the electrodes.primary standard A substance that is so pure that its amount (in mole) can be determined accurately from its mass.


primary structure The sequence of amino acids in a protein.prostaglandin A hormone that controls body temperature by causing blood vessels to constrict. It also increases the

SHUPHDELOLW\�RI�FDSLOODULHV��DOORZLQJ�ÀXLG�EXLOG�XS�LQ�WLVVXHV�protein Naturally occurring condensation polymer formed from amino acids.proton A positively charged particle found in the nucleus of an atom.proton NMR Nuclear magnetic resonance using the differences in the magnetic properties in 1H atoms in the compounds.

Often written as 1H NMR.purine base A derivative of purine, such as adenine or guanine.pyrimidine base A derivative of pyrimidine, such as cytosine or thymine.

qualitative analysis An analysis to determine the identity of the chemicals present in a substance.quality control� $QDO\VLV�E\�WKH�PDQXIDFWXUHU�RI�WKH�FRPSRVLWLRQ�RI�WKH�UDZ�PDWHULDOV�RU�WKH�¿QDO�SURGXFW�RI�DQ�LQGXVWULDO�SURFHVV�

to ensure they meet a particular standard.quantum of light A photon.quantitative analysis A determination of how much of each chemical is present in a substance.quantum of energy An indivisible ‘packet’ of energy.quench tower A tower used to cool hot gases rapidly.

reaction pathway A series of chemical reactions that convert a starting material into a product in a number of steps.reaction quotient The ratio of concentrations of reactants and products, as expressed in the equilibrium law for a reaction. The

reaction quotient is also known as the concentration fraction.reaction rate The speed at which a reaction occurs.reaction yield The proportion of product recovered from a reaction mixture, usually expressed as a percentage of the maximum

amount possible if the reaction were to proceed to completion.receptor site A molecule, usually a protein, that accepts and responds to a chemical such as a drug.rechargeable cell A secondary electrochemical cell. Recharging can occur because the products formed in the cell during

discharge remain in contact with the electrodes in a convertible form.redox reaction A reaction that involves the transfer of electrons from one chemical to another.redox titration A titration involving a redox reaction.reducing agent A reductant.reducing strength The ability of a substance to donate electrons and so reduce another.reductant A substance that causes another substance to be reduced; in the process the reductant is oxidised.reduction The acceptance of electrons by a chemical in a reaction.reference cell A cell that contains a reference material, such as pure solvent, and is used for the purpose of comparison in an

instrumental analysis.relative atomic mass The weighted mean of the relative isotopic masses of an element on the scale where carbon-12 is 12

exactly; symbol Ar.relative isotopic mass The mass of an atom of an isotope on the scale where carbon-12 is 12 exactly.relative molecular mass The relative mass of a molecule on the scale where carbon-12 is 12 exactly; symbol Mr. It is equal to

the sum of the relative atomic masses of the atoms in the molecule.renewable 5HVRXUFHV�DUH�UHQHZDEOH�LI�WKH\�DUH�QRW�¿QLWH��H�J��ZLQG�SRZHU��RU�FDQ�EH�UHSOHQLVKHG��H�J��ELRFKHPLFDO�IXHOV�restriction enzyme An enzyme that cuts a DNA molecule at each occurrence of a particular sequence of bases.retention time The time taken for a component to pass through a chromatography column.reversible reaction A chemical reaction in which the products can be converted back to the reactants.R

f value The ratio of the distance a component in a chromatogram has moved from the origin to the distance the solvent has

moved from the origin.risk assessment A formal way of identifying risks and assessing potential harm from a hazardous chemical in a particular

situation.rotational energy levels� 'LIIHUHQW�¿[HG�HQHUJLHV�WKDW�D�PROHFXOH�ZLWK�D�GLSROH�PRPHQW�FDQ�KDYH�DV�D�UHVXOW�RI�URWDWLRQ�DURXQG�

a bond.

salicylic acid A chemical used to make acetylsalicylic acid (aspirin).


salt bridge An electrical connection between the two half cells in an electrochemical cell; it is usually made from a material saturated with electrolyte solution.

sample cell A cell in an analytical instrument that contains the sample to be analysed.saturated hydrocarbon Hydrocarbons composed of molecules with only single carbon-to-carbon covalent bonds.saturated fat A fat derived from fatty acids that contain only single carbon-to-carbon bonds.secondary cell An accumulator or rechargeable cell. Recharging can occur because the products formed in the cell during

discharge remain in contact with the electrodes in a convertible form.secondary structure The coiling, folding or pleating of proteins due to the formation of weak bonds, e.g. hydrogen bonds,

between parts of the protein chain.self-ionisation of water The reaction of water with itself to form H3O

+ and OH– ions.semi-structural formula A formula that summarises the structural formula without giving the arrangement of atoms in space.shells Major energy levels around the nucleus of an atom in which electrons move; shells are numbered 1, 2, 3 etc.silver–zinc cell A galvanic cell generating a current when zinc is oxidised and silver oxide is reduced.solar cell A cell that converts solar energy into an electric current.solar energy Electromagnetic energy radiated from the Sun.solid stationary phase An adsorbent solid such as alumina or activated charcoal which is used as the stationary phase in

chromatography. The components of a mixture undergo adsorption to this solid as they are carried along by the mobile phase.

solvent A liquid in which other substances dissolve.solvent front The point reached by the mobile phase as it moves along the stationary phase in thin-layer chromatography.VSHFL¿F�KHDW�FDSDFLW\ The energy required to raise the temperature of one gram of a substance by 1°C.spectator ions Ions that remain in solution and are unchanged in the course of a reaction. Spectator ions are not included in

ionic equations.spectrum A display of the wavelengths of light that are either emitted or absorbed by a substance.spontaneous reactions Reactions that occur naturally, either in galvanic cells or when chemicals are mixed directly.standard half-cell potential The emf that is measured when a half cell, at standard laboratory conditions, is connected to a

standard hydrogen half cell. The standard half cell potential (E°) gives a numerical measure of the tendency of a half cell reaction to occur as a reduction reaction.

standard laboratory conditions (SLC) Conditions at which gas pressure is 1.0 atm (101.3 kPa), the concentrations of dissolved species are 1.0 M and the temperature is 25°C.

standard solution A solution of known concentration.standard temperature and pressure (STP) 0°C and 1 atm pressure.standards Chemicals of known composition used for comparison.stationary phase A solid, or a solid that is coated in a viscous liquid, used in chromatography. The components of a mixture

undergo adsorption to this phase as they are carried along by the mobile phase.steam cracking An industrial process in which hydrocarbons are diluted with steam and heated to produce smaller

hydrocarbon molecules.steam reforming A process for the production of hydrogen from natural gas and steam.steroids Molecules derived from cholesterol that perform a particular function, such as the sex hormones.strong acid An acid that readily donates hydrogen ions (protons). Strong acids have a large acidity constant, Ka.strong base A base that readily accepts hydrogen ions (protons).structural formula A formula that represents the three-dimensional arrangement of atoms in a molecule.structural isomers Molecules that have the same molecular formula but different structures.substitution reaction A reaction that involves the replacement of an atom or group of atoms by another atom or group of atoms.substrate The substance that is acted upon by an enzyme.sugars Carbohydrates that have a sweet taste.sustainable Able to support energy and resources into the future without depletion.synchrotron� $�SDUWLFOH�DFFHOHUDWRU�LQ�ZKLFK�WKH�PDJQHWLF�¿HOG�DQG�HOHFWULF�¿HOG�DUH�FDUHIXOO\�V\QFKURQLVHG�ZLWK�WKH�DFFHOHUDWHG�

electrons to produce intense electromagnetic radiation.syngas A gaseous mixture of carbon monoxide and hydrogen produced from the processing of biomass.synthesis The process of forming a new chemical substance from simpler ones.synthesis gas A gaseous mixture of carbon monoxide and hydrogen produced from the reaction of natural gas and steam.


synthetic pathway The series of chemical reactions required to produce a wanted material, often starting from simpler substances.

systematic name The name of a molecule as determined by a set of rules involving the number of carbon atoms and the location and type of functional groups present.

tertiary structure The three dimensional shape of a protein.therapeutic protein A protein used to treat a medical condition, e.g. insulin given to people with insulin-dependent diabetes

because their bodies are unable to make their own insulin.thermal cracking Production of small hydrocarbon molecules by heating larger hydrocarbons in the absence of a catalyst.thermal pollution The adverse effect on plants and animals of heat energy released into the environment.thermochemical equation A chemical equation that includes the enthalpy change of the reaction, "H.thin-layer chromatography (TLC)� &KURPDWRJUDSK\�XVLQJ�DV�WKH�VWDWLRQDU\�SKDVH�D�WKLQ�OD\HU�RI�¿QH�SRZGHU�VSUHDG�RQ�D�JODVV�

or plastic plate.thymine A base found in nucleic acids such as DNA. It is the complementary base of adenine.tidal power Electricity generated by the tidal movement of sea water.titration A process used to determine the concentration of a reagent in which one solution is added from a burette to a known

volume or mass of another substance.titre The volume of liquid, measured by a burette, used in a titration.total solids The total mass of solid material in a substance.transmittance The amount of light that passes through the sample.triglyceride A fat or oil molecule formed when three fatty acid molecules react with a glycerol molecule.

ultraviolet (UV) A region of the electromagnetic spectrum with wavelengths smaller than that of violet light.uncertainties Errors associated with measurements made during experimental work.unsaturated hydrocarbons Hydrocarbons composed of molecules with at least one carbon-to-carbon double or triple

covalent bond.UV–visible spectroscopy An analytical technique involving measurement of the UV–visible light absorbed by a substance.

vibrational energy levels� 'LIIHUHQW�¿[HG�HQHUJLHV�WKDW�PROHFXOHV�FDQ�KDYH�DV�D�UHVXOW�RI�EHQGLQJ�DQG�VWUHWFKLQJ�RI�ERQGV�volumetric analysis Analysis using measurement of volumes, e.g. titration.YROXPHWULF�ÀDVN� $�ÀDVN�XVHG�WR�PHDVXUH�SUHFLVH�YROXPHV�RI�VROXWLRQV�

waste An unwanted or unvalued substance that is discarded or discharged.waste heat Heat energy that cannot be converted to useful forms of energy.water content The amount of water in a substance, usually expressed as a percentage by mass.wavelength The distance between successive peaks in a wave.wavenumber Inverse of the wavelength of the radiation, measured in cm–1, used as a measurement of frequency in infrared

spectroscopy.weak acid An acid that donates protons to a limited extent. Weak acids have a small value of the acidity constant, Ka.weak base A base that accepts hydrogen ions to a limited extent.wet scrubbing A pollution-control technique used by industry to remove dust and pollutants from gases prior to their release into

the atmosphere.wind power Electricity generated by the movement of air.

yield The proportion of product in a reaction mixture, usually expressed as a percentage of the maximum amount possible.

Z group The side chain of an amino acid.zeolite A class of crystalline substances composed of aluminium, silicon and oxygen that have a three-dimensional honeycomb

structure of channels in which reactants lodge and readily undergo reaction.zinc–carbon dry cell A commonly used galvanic cell that generates an electric current by the oxidation of zinc and the reduction

of manganese dioxide at a carbon electrode.zwitterion A dipolar ion formed when the proton on the carboxy group of an amino acid molecule is transferred to the amino

functional group, as in +H3NCH2COO–.

heinemann chemistry 2 units 3 & 4 glossary

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