as chem ion

8/2/2019 As Chem ion

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Accuracy: The degree of conformity of a measured or calculated quantity to its actual (true) value.

Actinides: The bottom row of f block elements. These are all radioactive

Activated complex: A transitional structure in a chemical reaction that results from an effective collision

between molecules and that persists while old bonds are breaking and new bonds are forming.

Activation energy or EA: The minimum energy required to start a reaction by breaking bonds.

Addition polymerisation: A polymerisation reaction where monomers join together and the polymer is

the only product

Addition reaction: A reaction where two molecules combine to form a single product

Alcohols: Homologous series of organic molecules with an -OH functional group

Aldehydes: Homologous series of organic molecules containing the carbonyl group positioned at the

end to the carbon chain

Alicyclics: Organic molecules containing closed rings of carbon atoms which may contain single or

multiple carbon-carbon bonds

Aliphatic: Organic molecules containing straight or branched chain carbon skeletons which may contain

single or multiple carbon-carbon bonds

Aliphatic hydrocarbons: Hydrocarbons containing closed rings of carbon atoms which may contain

single or multiple carbon-carbon bonds

Aliquots: Equal measured volume of solution

Alkaline earth metals: A family of metals in Group 2 of the periodic table

Alkanes: Simplest homologous group of hydrocarbons with general formula cnh2n+2

Alkenes: Homologous series of hydrocarbons containing a double carbon-carbon bond with general

formula cnh2n

Alkyl group: An alkane molecule that has lost a hydrogen atom to attach to another carbon chain

Alkynes: Homologous series of hydrocarbons containing at least one triple carbon-carbon bond with

general formula cnh2n-2

Allotropes: Forms of the same element in the same physical state

Alpha radiation: Two protons and two neutrons (helium nuclei)

Amorphous carbon: Non crystalline forms of carbon e.g. Soot.

Anabolic steroids: Hormones used to encourage the growth of muscles and body mass.


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Anthropogenic climate change: Climate change due to activities of human beings e.g. Burning fossil

fuels, deforestation)

Antioxidants: Compounds which react with and inactivate free radicals.

Ar: Symbol for relative atomic mass

Arenes: Organic molecules derived from the benzene molecule containing a benzene ring with six

carbon atoms in their structure.

Atom: The smallest complete unit of an element. It consists of protons and neutrons in the nucleus

orbited by electrons.

Atom economy: Measure of how efficiently a reaction turns reactants into desired products. Equals the

molecular mass of the desired product divided by the molecular masses of all the products multiplied by

100.

Atomic crystals: Atoms held together by covalent bonds in a giant lattice structure.

Atomic mass unit: The mass of a carbon-12 atom divided by 12

Atomic number (Z): The number of protons in an atom of an element

Atomic radius: The distance of closest approach between two atoms

Atomisation: The breaking of the bonds in a molecule to leave atoms

Avogadro constant: The number of atoms of carbon in exactly 12g of carbon-12, 6.02 x 1023

Avogadro s law: Law proposed by Amedeo Avogadro in 1811; All gases contain equal numbers of

molecules at the same temperature and pressure

Balanced equation: A chemical equation where the numbers of atoms are equal on both sides and all

are in the form in which they undergo the reaction (ie complete molecules where relevant)

Base: The number base

Base peak: The largest peak (or the greatest trough) on the ir spectrum

Base units: The basic SI units of measurement

Bent linear: A molecule where three atoms are joined together but not in a straight line e.g. Water

Benzene: Organic compound with the molecular formula C6H6. Simplest arene compound with ring of

carbon atoms stabilised by delocalisation of electrons

Beta radiation: High energy electrons

Bio oil: See pyrolysis oil


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Bio polymers: Polmers made from materials produced from living, renewable resources such as plants

Biodegradable: Can be broken down by living organisms.

Biofuels: Fuels made from living material eg ethanol from the fermentation of maize

Blocks: Regions of the periodic table

Body centred cubic structure: Arrangement of ions in a lattice where each ion has 8 nearest neighbours

Bomb calorimeter: Calorimeter which gives accurate measure of enthalpy changes, particulary when a

substance is burned in oxygen.

Bond angles: Angle between two bonds in a molecule

Bond dissociation enthalpy: The energy required to break a particular bond, or the energy released

when a bond is formed.

Bond energy: The amount of energy needed to make or break a bond

Bond enthalpy: The energy contained in a chemical bond

Bond fission: Breaking the bonds between atoms in a molecule

Bond length: The average distance between the nuclei of atoms in a molecule

Born Haber cycle: Special type of enthalpy level diagram used to calculate the lattice energy of

siubstances.

Boundary: Separates the system from the surroundings in thermochemistry

Brittle: Breaks easily when hit

Buckminsterfullerene: See fullerenes

Calorimeter: Insulated container used to measure enthalpy change of a reaction

Carbanion: A species containing a negative charge produced by the heterolytic fission of a covalent

bond

Carbocation: The positively charged ion left when carbon has lost electrons in an electrophillic attack. A

species containing a positive charge produced by the heterolytic fission of a covalent bond.

Carbon capture: A process that removes carbon dioxide and prevents it being emitted.

Carbon footprint: Measure of the impact of human activity in terms of the amount of greenhouse gases

produced


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Carbon neutral: When the amount of carbon dioxide absorbed when a raw material is grown or a fuel is

formed equals the amount of carbon dioxide formed when it is burnt

Carbon offsetting: A method of reducing the effect of a carbon footprint e.g. By planting trees

Carbon sink: A reservoir of carbon compounds

Carbonium ion: See carbocation

Carboxylic acids: Homologous series of organic molecules with a -COOH functional group

Carcinogenic: Causes cancer

Cat cracker: Industrial vessel where catalytic cracking takes place

Catalyst: A substance which alters the rate of a chemical reaction without being used up.

Catalytic cracking or cat cracking: Breaking down long chain alkanes into shorter chain molecules which

are more useful as fuels and as compounds in industry. Catalysts such as zeolites are used to reduce the

temperature needed for the reactions to take place

Catalytic reforming: Process which involves breaking down the longer straight chain molecules from

crude oil and reforming them into shorter branched chain molecules (often isomers of the original

molecules) A platinum catalyst is often used to keep the temperatures required to a minimum

Cellulose: A polymer of glucose molecules found in the stems of plants

Centres of charge: Parts of a molecule where positive and negative charge is concentrated

Chain reaction: A reaction in which a change in one molecule causes changes in many other molecules

until eventually a stable molecule is formed

Charge density: The amount of electric charge per unit volume

Chemical bonds: Forces holding atoms together

Chemical properties: Properties which affect the way in which an element or compound reacts with

other substances

Chemical recycling: Chemically breaking down polymers into monomer units for reuse.

Chlorofluorocarbons or cfcs: Compounds containing chlorine, fluorine and carbon only, that is they

contain no hydrogen. They were formerly used widely in industry, for example as refrigerants,

propellants, and cleaning solvents.

Cis trans isomerism: Traditional method of naming geometric isomers based on the arrangement of

groups around a rigid bond


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Closed: A system which can exchange energy with the surroundings but not matter

Collisiontheory: Theory accounting for the effects of concentration, temperature and catalysts on

reaction rates.

Colorimeter: An instrument that measures the absorbance of particular wavelengths of light by a

specific solution. It is most commonly used to determine the concentration of a known solute in a given

solution.

Colorimetricanalysis: Analysis carried out using a colorimeter

Completion: A reaction where all of the reactants have been turned to products

Concentration: Measure of the amount of a solute dissolved in a solvent to form a solution

Condensation polymerisation: A polymerisation reaction where ,a small molecule such as water or

hydrogen chloride is lost when two monomer molecules combine.

Condensation reaction: A reaction where two molecules combine to form a larger molecule and a small

molecule such as water or hydrogen chloride is lost

Conductimetric analysis: Analysis carried out by measuring changes in conductivity of solutions

Contrails: Condensation trails and artificial cirrus clouds made by the exhaust of aircraft engines which

precipitate a stream of tiny ice crystals in moist, upper atmosphere

Coordination number: The number of close neighbours to an ion in a lattice structure

Corrosive: A substance which breaks down or destroys materials including skin

Coulombslaw: Law which states that the force of attraction between ions is related to the charge on

the ions and the distance between them

Covalentbond: A chemical bond formed when two or more atoms share electrons to gain a full, stable

outer shell

Covalentbonding: A chemical bond formed when two or more atoms share electrons to gain a full,

stable outer shell

Covalentbonds: Strong bonds which result from sharing electrons during covalent bonding

Cracking: See catalytic cracking

Crudeoil: Unprocessed oil, a fossil fuel which is extracted from under the ground

Curlyarrows: Symbol used to represent the movement of a pair of electrons

Dblock: Region of the periodic table containing elements with their outer electrons in the d subshell


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Dblockelements: Elements with the outermost electrons in the d subshell

Dativecovalentbond: A dative covalent bond is where both of the shared electrons come from the

same atom

DebyeorD: Unit of dipole moment

Delocalisedelectrons: Electrons which are not associated with one particular atom but are free to

move.

Derivedunits: Units of measurement derived from the basic SI units

Diatomic: A molecule containing two atoms

Dieseloil: One of the heavier fractions of crude oil used in diesel engines and as fuel for industrial

boilers. Can also be used in a catalytic cracker to yield other chemicals

Dimers: Pairs of molecules held together by dative covalent bonds

Dipole: A positive charge and a negative charge separated by a short distance

Dipoleinteractions: Forces of attraction between charge centres in different molecules

Dipolemoment: For a pair of opposite charges of magnitude of the dipole moment is defined as the

magnitude of the charge times the distance between them and the defined direction is toward the

positive charge.

Displacementreaction: A reaction where a more reactive element displaces a less reactive element in

aqueous solution

Displayedformula: Formula which shows both the relative placing of the atoms and the number of

bonds between them

Disproportionation: Simultaneous oxidation and reduction

Dissipated: Energy irreversibly lost to the system

Dotandcrossdiagrams: A way or representing electrons to model bonding between atoms

Doublebond: The bond formed when two atoms share two pairs of electrons

Doublesalt: Crystal containing two different salts in a 1:1 ratio

Ductile: Can be drawn out into wires

Dynamicequilibrium: See equilibrium

Eisomer: Isomer with higher priority groups on opposite sides of a rigid bond.


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EZisomerism: IUPAC system for naming geometric isomers based on the atomic numbers of the atoms

attached around a rigid bond

Electroncloud: Arrangement of electrons in an atom

Electrondensity: the areas in the electron cloud of an atom where the electrons are most likely to be

found

Electrondensitymaporplot: Map plotting the areas where the probablility of finding an electon is

highest. The diffraction patterns produced when x-rays are passed through a crystal and diffracted by

the electrons in the ions or atoms in the structure.

Electronpairrepulsiontheory: The theory used to explain the shapes of molecules using the idea that

electron pairs are arranged as far from each other as possible

Electronspin: The rotation of electrons clockwise or anticlockwise creating a magnetic field

Electronegativity: The tendency of the atoms of an element to gain electrons

Electronicconfiguration: The arrangement of the electrons in an atom in their subshells and orbitals

Electronicstructure: The arrangement of electrons in an atom in its main energy levels and sub-levels

Electrons: Sub-atomic particles with a negative charge which orbit the nucleus of an atom

Electrophiles: Positively polarised, electron seeking groups eg H+

Electrophilic: Attracted to electrons

Electrophilicadditionreaction: A reaction in which an electrophile is attracted to an area of high

electron density and joins onto the molecule

Electrophilicattack: Effect of an electrophile on a molecule in a reaction, removing electrons

Electrostatic: Relating to electric charges that do not move

Electrostatictheory: Like charges repel, opposite charges attract

Electrovalentbond: See ionic bond

Element: A substance that cannot be broken down chemically into simpler substances. All the atoms of

an element contain the same number of protons

Eliminationreaction: A reaction in which a small molecule is removed from an organic molecule to

produce a double bond.

Emissionspectrum: See line spectrum


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Empiricalformula: Simplest formula of a compound showing the whole number ratios of the atoms

present

Endpoint: The stage in a reaction where the indicator changes colour showing that exact reacting

volumes of the two solutions are present

Endothermic: A reaction which takes in energy from the surroundings

Energeticstability: Stability of a compound with respect to its elements in terms of bond enthalpy

Energetics: The study of energy transfers between reacting chemicals and their surroundings

Energyrecovery: Methods of recovering some of the energy used in the production of polymer products

by burning them as fuels for electricity production etc

Entgegen: opposite

Enthalpychange: The change in the energy content of a system held at constant presssure

Enthalpychangeofreaction: The energy change which takes place during a chemical reaction

EnthalpyH: The energy content of a system at constant pressure

Enthalpyleveldiagram: Diagram used to represent the enthalpy changes during a reaction

Epitestosterone: Hormone similar to testosterone

Equilibriumorequilibria: A situation with a reversible reaction where the rate of the forward reaction is

equal to the rate of the reverse reaction so there is no apparent changes in concentration of reactants

and products. The plural is equilibria.

Ethers: An homologous series

Excited: Term used to describe electrons when they are raised from one energy level to another within

an atom

Exothermic: A reaction which releases energy into the surroundings

Fblock: Region of the periodic table containing elements with their outer electrons in the f subshell

Fblockelements: Elements with the outermost electrons in the f subshell

Facecentredcubicstructure: Arrangement of ions in a lattice where each ion has 6 nearest neighbours

Feedstockrecycling: See chemical recycling

Fingerprintregion: The region to the right-hand side of the ir spectrum (from about 1500 to 500 cm-1)

usually contains a very complicated series of absorptions. These are mainly due to all manner of bending

vibrations within the molecule.


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Fireretardants: Materials that inhibit or resist the spread of fire.

Firstionisationenergy: The energy needed to remove the first electron from an atom

Flamephotometer: An instrument used for measuring the spectral intensity of metals present in the

metallic salt

Flametest: Test used to detect certain metal cations by observing the colour of the flame

Fraction: The liquid collected at a particular temperature during primary distillation

Fragmentation: The process in a mass spectrometer that causes a positive ion to split into pieces, one of

which is a positive fragment ion

Freeradicals: Atom or molecule with an unpaired electron - for example formed on the breaking of a

covalent bond

Fullerenes: A family of ball-shaped carbon molecules with the commonest one C60 calledbuckminsterfullene.

Functionalgroup: Atom or group of atoms which is typical of a particular homologous series (organic

family) and which plays an important part in determining the chemical properties of the molecule

Gammaradiation: Electromagnetic radiation

Gasoil: Similar to diesel oil but less useful in a cracker

Gasification: Breakdown of solid hydrocarbons in a limited supply of oxygen to produce syngas.

Gasoline: A mixture of liquid hydrocarbons widely used as motor fuel (C5-C10)

Generalformula: A formula which applies to all members of an homologous series and describes the

number of carbon atoms and their relationship to the other atoms

Geometricisomerism: Stereoisomer - and isomer in space. A chemical compound which has the same

molecular formula as another but a different geometric configuration because atoms or groups of atoms

are attached on either side of a double bond or other rigid bond

Geometricisomers: See geometric isomerism

Giantatomicstructures: See atomic crystals

Giantlatticestructure: Arrangement of ions in an ionic substance

Giantmolecularstructures: See molecular crystals

Globalwarming: A measured increase in the temperature at the surface of the earth over a period of

time


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GlobalwarmingpotentialorGWP: A measure of the effectiveness of different gases have in increasing

global warming

Greenhouseeffect: The trapping of some of the energy absorbed by the earth from the sun and

reradiated from the surface by greenhouse gases in the atmosphere. Some of the energy is reradiated

back down to earth again by these greenhouse gases and this is known as the greenhouse effect.

Greenhousegases: Atmospheric gases which reduce the loss of heat by radiation from the Earth s

atmosphere, contributing to the greenhouse effect eg carbon dioxide, methane

Groundstate: The lowest energy state for an atom

Groups: Vertical columns of periodic table

Halfequations: Part of an equation for a redox reaction showing oxidation or reduction of one species.

Two half equations added together can produce an ionic equation

Half-life: The time it takes for half of the atoms in a sample of radioactive material to decay

Halogenoalkanes: Homologous series of organic molecules in which one or more of the hydrogen atoms

within an alkane has been replaced by a halogen atom.

Halogens: A family of reactive non-metals in Group 7 of the periodic table.

Hazard: Potential to do harm

Heatcapacity(C): The amount of heat required to raise the temperature of an object by 1K

Heatexchanger: A device built for efficient heat transfer from one place to another. In a chemical

factory waste energy from one place can be used efficiently elsewhere.

Hessslaw: Law stating that the total enthalpy change for a reaction is independent of the route taken

Heterogeneousreaction: A reaction which takes place at the boundary of two phases

Heterolyticfission: Fission which involves the unequal sharing of the electrons of a covalent bond, so

that both electrons go to one atom when then covalent bond is broken.

HighdensitypolytheneorHDPE: Ethene polymer with relatively few branched chains so relatively

dense with higher melting temperature than low density polyethene

Homogeneousreaction: A reaction which takes place in a single phase.

Homologousseries: Family of organic molecules

Homolyticfission: Fission which involves the equal sharing out of the electrons in a bond, so that each

atom receives one electron when the bond is broken


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Hundsrule: Rule stating that when electrons are placed in a set or orbitals with equal energy, they

spread out to maximise the number of unpaired electrons

Hydration: The process where water molecules arrange themselves around ions in solution

Hydrationenthalpy: Energy released when 1 mole of gaseous ions are dissolved in excess water

Hydrocarbons: Organic compounds with molecules containing only carbon and hydrogen

Hydrochlorofluorocarbonsorhcfcs: a class of haloalkanes where not all hydrogen has been replaced by

chlorine or fluorine. They are used primarily as chlorofluorocarbon (CFC) substitutes, as the ozone

depleting effects are only about 10% of the cfcs.

Hydrogenbond: A special type of dipole-dipole force that exists between an electronegative atom and a

hydrogen atom bonded to another electronegative atom. This type of force always involves a hydrogen

atom and the energy of this attraction is close to that of weak covalent bonds (155 kj mol-1),

Hydrogencell: A new technology for powering vehicles based on the oxidation of hydrogen with water

as the waste product

Hydrolysis: A reaction where a substance is split up by water (or dilute acid or alkali)

Hydroxylgroup: An O-H group

Immiscible: Liquids which do not mix but form separate layers.

Incompletecombustion: Burning when the supply of oxygen is limited

Index: The power to which a base number is raised

Induceddipole: A dipole set up by the close proximity of a strong charge

Inert: Non-reactive

Infraredspectrometer: An instrument for producing an infrared spectrum

Infraredspectrum: A graph showing the record produced when an infrared spectrometer scans a range

of ir wavelength and the detector records how strongly the sample absorbs each wavelength

Initialrateofreaction: The rate of reaction at the start of a reaction.

Initiate: Start/supply the initial energy for a reaction

Inorganicchemistry: Study of all the 91 naturally occurring chemical elements and their compounds,

including carbon and its oxides and carbonates.

Instantaneousdipole: A temporary dipole set up in a molecule


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Instantaneousdipoleinduceddipoleinteractions: Forces between neighbouring molecules that provide

the means of bringing non-polar molecules together in a liquid at low temperatures.

Instantaneousdipoleinstantaneousdipoleforces: See London dispersion forces

Intermolecularforces: Forces between molecules

Intramolecularforces: Forces within molecules

Ion: An atom which has lost or gained electrons to take a positive or negative charge

Ionmicroscope: A microscope which uses helium ions instead of light to form an image giving very high

levels of magnification

Ionicbond: Strong force of attraction between oppositely charged ions formed during ionic bonding.

The electrostatic forces holding two oppositely charge ions together

Ionicbonding: A chemical bond formed when atoms gain or lose electrons to form positive or negativeions. The loss or gain in electrons gives the ion a complete outer shell of electrons

Ioniccrystals: Crystals formed by giant ionic lattices

Ionicequation: Reaction equation which only shows the ions involved in a reaction

Ionic radius: Term used to describe the size of ions

Ionisation: The complete removal of an electron from an atom

Ionisationenergy: The energy change associated with the removal of an electron from an atom or ion

Irritant: A substance which causes irritation of the skin

Isoelectronic: An ion with the same number and arrangement of electrons as an atom of another

element

Isolated: A system where the boundary prevents matter and energy entering or leaving

Isomerism: Where two or more compounds have the same molecular formula but with the atoms

arranged differently

Isomers: Two or more compounds with the same molecular formula but with the atoms arranged

differently

Isotopes: Atoms of the same element with the same atomic number but with different numbers of

neutrons giving them different mass numbers

IUPAC: International Union of Pure and Applied Chemistry


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Kerosene: The fraction of crude oil used for aircraft fuel and also as a source of other useful chemicals in

the cracking process

Ketones: Homologous series of organic molecules containing at least one carbonyl group which is never

positioned at the end to the carbon chain

Kineticstability: When the activation energy of a reaction is so large that no molecules in the reaction

mixture have sufficient energy to overcome it and so the reaction does not take place

Lanthanides: The top row of f block elements

Lattice: Structural arrangement of a solid

Latticeenergy: The energy released when an ionic lattice is formed. A measure of the strength of bonds

in an ionic compound. It is equivalent to the amount of energy required to separate a solid ionic

compound into gaseous ions.

Lawofoctaves: Law developed by John Newlands in an attempt to arrange the elements in order of

their atomic masses.

LeChateliersprinciple: When an equilibrium reaction mixture is subjected to a change in conditions,

the composition of the mixture adjusts to counteract the change

Lifecycleanalysis: See life cycle assessment

Life cycle assessment or LCA: The investigation and valuation of the environmental impacts of a given

product or service caused or necessitated by its existence.

Lime water: A solution of calcium hydroxide in water used as a positive test for carbon dioxide gas.

Line spectrum: The pattern which results when the light given out by a gas when an electrical charge is

passed through it is split to form a spectrum

Linear: All of the atoms in a molecule are in a straight line

LiquidpetroleumgasorLPG: Propane which is liquified under low temperatures and high pressures for

storage and transport

London dispersion forces: The forces that exist in non-polar molecules that involve an accidental dipole

that induces a momentary dipole in a neighbour.

London forces: See London distribution forces

Lone pair: Two non-bonding electrons in a molecule

Low density polythene: Ethene polymer with branched chains - low density, low melting temperature.


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Macroscopic properties: Those properties that an external observer can see and measure with a naked

eye

Malleable: Can be hammered into sheets

Markovnikovs rule: Rule which states that when a hydrogen halide is added to an alkene, the hydrogen

is most likely to add to the carbon atom which already has the most hydrogen atoms attached to it

Massnumber (A): The number of neutrons plus the number of protons in the nucleus of an atom

Mass spectrometer: Instrument for obtaining a mass spectrum that can be used to measure the relative

masses of isotopes or to find the relative abundance of the isotopes in a sample of an element

Mass spectrum: The data produced by a mass spectrometer

Maxwell Boltzman model: A model for expressing the distribution of energy among the molecules of a

gas in thermal equilibrium

Mean bond enthalpy: The mean (average) value of the bond dissociation enthalpy of a particular type of

bond over a wide range of different compounds.

Mechanical recycling: Physically breaking down plastics into smaller pieces before reprocessing

Melting temperature: The temperature at which a pure solid is in equilibrium with a pure liquid at

atmospheric pressure

Metallic bonding: Bonding in metals with positive metal ions embeeded in a sea of delocalised electrons

Metalloids: Elements which is not a metal but which has some characteristics of a metal eg conducts

electricity

Metals: Elements which are good conductors of heat and electricity, can be hammered into sheets and

drawn into wires, usually shiny and with the exception of mercury solids at room temperature

Micromoles: 1.0-6 mol dm-3

Microscopic processes: processes on a molecular scale

Millimoles: 1.0-3 mol dm-3

Miscible: Liquids which completely mix to form a single layer

Molar: Concentration in mol dm -3

Molar enthalpy of vaporisation: Energy required to change 1 mole of a liquid to a vapour at its boiling

temperature

Molar mass (M):The relative atomic or molecular mass in grams


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Molarsolution: A solution of concentration 1 molar (1 mol dm-3)

Molar volume (Vm): The volume occupied by a mole of any gas under standard conditions of 1 atm

pressure and 298K

Molarity: See molar

Moleormol: The amount of substance that contains the same number of particles as there are atoms in

exactly 12g of carbon-12, the relative atomic or molecular mass of a substance in grams

Molecularcrystals: Covalently bonded molecules held together in giant structures by intermolecular

forces as a result of partial ionic character in the covalent bond

Molecularequation: Reaction equation which shows the complete formula of every substance involved

in the reaction

Molecularformula: Formula of a compound showing how many of each atom there are

Molecularionpeak: The peak corresponding to the M+ ion- the peak with the highest m/z value

Moles per cubic decimetre: Measure of the concentration of a solution

Monomer: A small molecule, for example an alkene, that can be joined to many other small molecules

to form a much larger molecule

Nanoparticles: Small particles with at least one dimension less than 100 nm.

Nanoprobes: Devices for seeing very small objects

Nanorods: A material made by compressing carbon-60 molecules. It is even harder than diamond.

Nanorods can also be made of other substances e.g. Silicon carbide.

Nanotubes: Cylindrical carbon molecules have novel properties that make them potentially useful in

many applications in nanotechnology, electronics, optics and other fields of materials science. They

exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat.

Natural climate change: Climate change due to naturally occurring processes.

Naturalgas: A gaseous fossil fuel often found in association with crude oil. Largely made up of methane

Naturalpesticides: Pesticides derived from plants or other living organisms

Neutrons: Electrically neutral sub-atomic particle found in the nucleus of an atom. Mass slightly greater

than that of a proton.

Noble gases: Group 8, unreactive gases

Non aqueous solvents: A solvent other than water


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Non-metals: All the elements which are not metals

Nucleons: The sub-atomic particles found in the nucleus of an atom - the protons and the neutrons

Nucleophile: An electron donor, attracted to positive ions. An atom or group of atoms that is attracted

to a positive charge. A nucleophile is negatively charged or contains a lone pair of electrons.

Nucleophilicattack: Effect of a neutrophile on an ion in a reaction, donating electrons

Octanerating: Rating for fuel which indicates the proportion of branched chain to straight chain alkanes

in the fuel mixture

Octetrule: Rule stating that when elements react they tend to do so in a way which results in an outer

shell containing eight electrons

Orbital: The region where an electron is most likely to be found

Organicchemistry: Study of carbon compounds with the exception of the simplest compounds such asthe oxides and carbonates

Overallionicequation: Overall reaction equation showing what happens overall to the ions in the

reaction

Oxidation: Reaction in which electrons are lost

Oxidationnumbers: The charge that an element would have if it were totally ionically bonded.

Oxidisingagent: A substance which oxidises another substance but is itself reduced.

Pblock: Region of the periodic table containing elements with their outer electrons in the p subshell

Pblockelements: Elements with the outermost electrons in the p subshell

Paraffins: Old, non-systematic name for the alkanes

Partspermillion (ppm): Mass of the solute divided by the total mass of the solution multiplied by a

million

Peaks: Characteristic wavelength of a vibration of a particular group leads to a maximum amount of ir

radiation being absorbed. They are in fact shown as troughs on the ir spectrum.

Pentagonal bipyramid: A molecule with three bonds in a plane with bond angles of 120o and one bond

at right angles above and one bond at right angles below the plane

Percentage transmission: The variable recorded on the y-axis of an ir spectrum

Periodic law: Law stating that the properties of elements are a function of their atomic numbers.

Periodic properties: Properties which show clear patterns in the periodic table


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Periodic table: Table arranging the elements in order of their atomic number

Periodicity: Repeating patterns of elements in the periodic table

Periods: Horizontal rows of the periodic table

Permanent dipole: A distribution of charge within a molecule

Pesticides: Chemicals that kill animal pests

Petroleum: See crude oil

Physical properties: Properties which do not involve the chemical nature of the element or compound

eg melting temperature, density, conductivity etc

Pi bond: Double carbon-carbon bond

Polar bond: A covalent bond where the pair of bonding electrons is not evenly distributed

Polar molecule: A molecule with an overall dipole ,taking into account any dipole across bonds

Pole: One half of a dipole

Polychloroethene: Polymer of chloroethene

Polyethene: Polymer made from repeating ethene monomer units

Polymer: Large molecule made up of long chains of smaller units joined together

Polymerisation reaction: A reaction in which many monomer units are joined together to form a long

chain polymer molecule

Polypropene: Polymer of propene

Position of equilibrium: The extent to which a reaction has moved to completion

Post transition metals: Metals found to the right hand side of the periodic table after the transition

metals

Precise: Results made to the maximum accuracy permitted by the apparatus

Primary alcohol: An alcohol where the hydroxyl group is attached to a carbon atoms itself bonded totwo or three other hydrogen atoms.

Primary distillation: Process by which crude oil is turned into useful chemicals

Primary halogenoalkanes: Halogen atom is attached to a carbon atom attached to two or three

hydrogen atoms


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Principal quantum number (n): The number assigned to electron shells, which indicates the size of the

shell and the distance from the nucleus

Principle of conservation of energy: Principle stating that the total energy content of the universe is

constant.

Propagation: A reaction which sets of other reactions

Protons: Sub-atomic particle with positive charge found in the nucleus of an atom

Pyramidal: A molecule such as ammonia with a pyramid shape

Pyrolysis: Method of breaking down polymers using heat in the absence of oxygen

Pyrolysisoil: A possible alternative for petroleum. It is extracted by pyrolysis from dried biomass in a

reactor at temperature of about 500 degrees centigrade with subsequent cooling.

Qualitative: Identifying the different constituents (elements, ions or atoms) that are present in asubstance

Quantitative: Measuring the different quantities of constituents (elements, ions or atoms) that are

present in a substance

Quantummechanics: Branch of mathematics needed to understand atomic structure in detail

Quench: Cooling a sample rapidly to slow all reactions to enable analysis to be carried out.

Quicklime: The old name from calcium oxide

Radioactivedecay: The process by which an unstable nucleus breaks up to become more stable and

emits alpha, beta or gamma radiation

Radiocarbondating: Using the ratio of C-12 to C-14 to date once-living material

Rateofreaction: The rate of a reaction is the speed at which a reaction happens.

Reactionmechanism: The mechanism by which a reaction takes place. A possible route that a reaction

might follow showing the intermediate stages.

Reactionprofile: Graph that show the change in energy as a function of the progress of the reaction.

Reactivemetals: The s block elements

Redoxreaction: A reaction where oxidation and reduction take place

Reducingagent: A substance which reduces another substance but is itself oxidised.

Reduction: Reaction in which electrons are gained.


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Refinerygas: The lightest fraction of crude oil (C1 C4)

Refluxcondenser: A vertical condenser which condenses escaping vapours so they fall back into the

reacting flask.

Relativeabundance: Measure of the percentage of different isotopes in a sample of an element

RelativeatomicmassorRAM: The atomic mass of an atom relative to an atom of carbon-12

Relativeatomicmassscale: The scale by which chemists compare the mass of all atoms to the mass of a

standard carbon-12 isotope

Relativeformulamass: The sum of all the relative atomic masses of all the atoms in a chemical formula

Relativegreenhousefactor: A comparison of the effect different gases have on absorbing IR radiation.

The value for carbon dioxide is 1.

Relativemolecularmass (Mr): The sum of all the relative atomic masses of all the atoms in a chemicalformula of a covalent compound

Reliability: Results that, if repeated, will give the same outcome.

Residue: A viscous mixture of hydrocarbons with high boiling points produced during fractional

distillation of crude oil. Can be used as fuel for power station furnaces or large ships or further

fractionated to yield other useful substances.

Risk: The chance of a hazard causing harm

Riskassessment: Identifying the risks associated with a course of action and reducing them as far as

possible

Rocksaltstructure: The packing of ions found in sodium chloride

Sblock: Region of the periodic table containing elements with their outer electrons in the s subshell

Sblockelements: Elements with the outermost electrons in the s subshell

Saturated: Fatty acid containing only carbon-carbon single bonds

Secondionisationenergy: The energy needed to remove a second electron from an atom/ion

Secondaryalcohol: An alcohol where the hydroxyl group is attached to a carbon atoms itself bonded to

one other hydrogen atoms.

Secondaryhalogenoalkanes: Halogen atom is attached to a carbon atom attached to one hydrogen

atom


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Shells: The regions in which electrons are concentrated around a nucleus, representing different energy

levels of the electrons.

Sigmabond: Single carbon-carbon bond

Skeletalformula: Formula which simply shows the bonds and the functional group often used for ring

compounds

Slakedlime: The old name for calcium hydroxide

Slaking: The exothermic process taking place when water is added to calcium hydroxide

Solubility: Mass of a solute dissolving in 100g of solvent at a particular temperature

Solute: Solid, liquid or gas dissolved in a liquid to form a solution

Solution: A liquid containing a dissolved solid, liquid or gas

Solvent: Liquid in which substances dissolve to form a solution

Spacefillingmodels: Models showing the shape of molecules in three dimensions.

Specificheatcapacityc: The heat capacity per unit mass of a particular substance

Spectatorions: Ions which appear in the same form on both sides of an ionic equation and can

therefore be left out as they are not involved in the reaction

Stability: Description of how readily a compound breaks down into its elements or reacts with other

compounds

Standard enthalpy change of atomisation: The enthalpy change when one mole of its atoms in the

gaseous state is formed from the element under standard conditions

Standardenthalpychangeofcombustion: The enthalpy change when one mole of a substance is

completely burnt in oxygen under standard conditions.

Standardenthalpychangeofformation: The enthalpy change when one mole of the compound is

formed from its elements under standard conditions

Standardenthalpy change of neutralisation: The enthalpy change when one mole of acid is just

neutralised by an alkali in their standard states at 25oc (298K) and in solutions containing 1 mol dm-3

Standard enthalpy change of reaction: The enthalpy change of a reaction measured under standard

conditions of temperature and pressure (1atm and 298K)

Standard form: A way of writing a number between 1-10 multiplied by 10 raised to the appropriate

power


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Standard solution: A solution of known concentration

Standard temperature and pressure STP: Conditions used for measuring the molar volumes of gases - 1

atm pressure and 298K (25oc)

Starch: A polymer of glucose molecules

State symbols: Symbols used to indicate the physical state of a chemical in a reaction. S is solid, l is

liquid, g is gas, aq is aqueous.

Steady state: a situation in which all variables are constant in spite of ongoing processes that strive to

change them.

Stereoisomerism: When two or more compounds with the same molecular formula have a the three

dimensional arrangement of the bonds which allows different orientations in space so the molecules

cannot be superimposed on each other.

Stereoisomers: Two or more compounds with the same molecular formula where the three dimensional

arrangement of the bonds allows different orientations in space so the molecules cannot be

superimposed on each other.

Structuralformula: Formula which shows both the number of atoms in a molecule and the way in which

they are arranged relative to each other

Structuralisomerism: Where two or more compounds have the same molecular formula but with the

atoms connected together in a different order

Structuralisomers: Two or more compounds with the same molecular formula but with the atoms

connected together in a different order

Subshell: Regions of differing energy within a shell, described by the letters s,p,d,f,g etc

Substitutionreaction: A reaction in which an atom or group of atoms is replaced by a different atom or

group of atoms.

Superconducting: At very low temperatures certain materials have very low electrical resistance and so

become superconductors

Surroundings: Everything around a chemical reaction

Syngas: Mixture of hydrogen and carbon monoxide which can be used in a number of chemical

processes

Synthesise: To make in a laboratory

Syntheticpesticides: Pesticides which are not naturally occurring - they have been synthesised in the

laboratory


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System: A chemical reaction

Systeme International or SI: The common internationally used system of measurements

Termination: A reaction which completes a chain reaction

Tertiaryalcohol: An alcohol where the hydroxyl group is attached to a carbon atoms itself bonded to no

other hydrogen atoms.

Tertiaryhalogenoalkanes: Halogen atom is attached to a carbon atom attached to no hydrogen atoms

Testosterone: Male sex hormone

Tetrahedral: The angle within a molecule with four covalent bonds e.g. Methane 109.5o

Thermochemistry: The study of energy transfers in chemical reactions

Thermodynamicstability: See energetic stability

Titration: A process for finding the exact volumes of different solutions which react using an indicator.

Titrimetricanalysis: See volumetric analysis

Transition: Energy changes which take place within the atom a electrons move from one energy level to

another

Transitionmetals: Another name for the d block elements

Triads: Groups of three elements in an early attempt to group the elements

Trigonalplanar: A triangular shape with all three lines/orbitals in the same plane

Triplebond: The bond formed when two atoms share three pairs of electrons

Unsaturated: Fatty acid containing at least one carbon-carbon double bond

Unstable: An atom in which the forces which make up the nucleus are unbalanced and there is an excess

of internal energy. As a result an unstable atom will be radioactive as eventually the unstable nucleus

emits radiation to become stable.

VanderWaalsforces: Very weak attractive forces between induced dipoles in adjacent molecules

Volatility: The ease with which a liquid turns into a gas. Volatility decreases as boiling temperature

decreases.

Volumetricanalysis: Chemical procedure used for determining the concentration of a solution. A known

volume of a solution of unknown concentration is reacted with a known volume of a solution of known

concentration (standard).


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Weightedmean: A mean based on both the abundance of an isotope and its RAM

Yield: The quantity of a product obtained from a chemical reaction

Zisomer: Isomer with both higher priority groups on the same side of a rigid bond

Zusammen: Together

as chem ion

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