F322 Key words

Hydrocarbons - organic compounds that contain carbon and hydrogen only

Saturated hydrocarbon - a hydrocarbon with single bonds only

Unsaturated hydrocarbon - a hydrocarbon containing carbon-carbon multiple bonds

Aliphatic hydrocarbon - hydrocarbon with carbon atoms joined together in straight or branched chains

Alicyclic hydrocarbon - hydrocarbon with carbon atoms joined together in a ring structure

Nomenclature - a system of naming compounds

Alkyl group - an akane with a hydrogen atom removed

Empirical formula - the simplest whole number ratio of atoms of each element present in a compound

Molecular formula - the actual number of atoms of each element in a molecule

General formula - the simplest algebraic formula of a member of a homologous series e.g. for an alkane it is CnH2n+2 

Structural formula - the minimal detail that shows the arrangement of atoms in a molecule e.g. for butane it is CH3(CH2)2CH3

Displayed formula - the relative positioning of atoms and the bonds between them 

Skeletal formula - the simplified organic formula, shown by removing hydrogen atoms leaving just a carbon skeleton and associated functional groups

Homologous series - a series of organic compounds having the same functional group but with each successive member differing by CH2

Functional group - the part of an organic molecule responsible for its chemical reactions

Structural isomers - compounds with the same molecular formula but different structural arrangements of atoms (different structural formulae)

Stereoisomers - compounds with the same structural formula, but with a different arrangement in space

E/Z isomerism - an example of stereoisomerism in which different groups attached to each carbon of a C=C double bond may be arranged differently in space because of restricted rotation of the C=C bond

cis-trans isomerism - special case of E/Z isomerism in which two of the substituent groups are the same

Homolytic fission - the breaking of a covalent bond, with one of the bonded electrons going to each atom, forming two radicals

Radical - a species with an unpaired electron

Heterolytic fission - the breaking of a covalent bond with both of the bonded electrons going to one of the atoms forming a cation (+) and an anion (-)

Nucleophile - an electron pair donor

Electrophile - an electron pair acceptor

Fractional distillation - the separation of the components in a liquid mixture into fractions which differ in boiling point by means of distillation (using a fractionating column)

Cracking - refers to the breaking down of long-chained saturated hydrocarbons to form a mixture of short-chained alkanes and alkenes

Catalyst - substance that increases the rate of a chemical reaction without being used up in the process

Addition reaction - a reactant is added to an unsaturated molecule to make a saturated molecule

Substitution reaction - an atom (or group of atoms) is replaced with a different atom (or group)

Elimination reaction - the removal of a molecule from a saturated molecule to make an unsaturated molecule

Initiation - first step in a radical substitution in which the free radicals are generated by UV

Propagation - the two repeated steps in radical substitution that build up the products in a chain reaction 

Termination - the step at the end of a radical substitution when two radicals combine to form a molecule

A pi-bond - reactive part of a double bond formed above and below the plane of the bonded atoms by sideways overlap of p-orbitals

Polymer - long molecular chain built up from monomer units 

Monomer - small molecule that combines with many other monomers to form a polymer

Addition polymerisation - the process in which unsaturated alkene molecules add on to a growing polymer chain to form a long saturated molecular chain 

Addition polymer - long molecular chain formed by repeated addition reactions of many unsaturated alkene molecules

Repeat unit - specific arrangement of atoms that occurs in the structure over and over again (written in square brackets with the symbol n outside)

Biodegradable material - material that is broken down naturally in the environment by living organisms

Volatility - the ease that a liquid turns into a gas. It increases as boiling point decreases

Reflux - the continual boiling and condensing of a reaction mixture to ensure that the reaction takes place without the contents of the flask boiling dry

Esterification - the reaction of an alcohol with a carboxylic acid to produce an ester and water

Dehydration - an elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule

Hydrolysis - reaction with water or aqueous hydroxide ions that breaks a chemical compound into two chemical compounds

Percentage yield -     actual amount of product (in moles)       x100
                            theoretical amount of product (in moles) 

Atom economy -     molecular mass of the desired product       x100
                          sum of molecular masses of all products 

Molecular ion - the positive ion formed in mass spectrometry when a molecule loses an electron

Fragmentation - the process in mass spectrometry that causes a positive ion to split into pieces, one of which is a positive fragment ion

Enthalpy, H - the heat content that is stored in a chemical system

Exothermic - a reaction where the enthalpy of the products is smaller than the enthalpy of the reactants, resulting in heat loss to the environment -ΔH

Endothermic - a reaction where the enthalpy of the products is greater that the enthalpy of the reactants, resulting in heat being taken from the environment +ΔH

Activation energy - the minimum energy required to start a reaction by the breaking of bonds

Standard conditions - a pressure of 100kPa, temperature usually 298K and a concentration of 1M

Enthalpy change of reaction - the enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all species in their standard states

Enthalpy change of formation - enthalpy change that takes place when one mole of a compound is formed from its constituent elements in their standard states under standard conditions

Enthalpy change of combustion - enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions, all species in their standard states

Specific heat capacity, c - energy required to raise the temperature of 1g of a substance by 1 degrees C

Average bond enthalpy - the average enthalpy change that takes place when breaking by homolytic fission 1 mol of a given type of bond in gaseous molecules

Hess's law - if a reaction can take place by more than one route, the total enthalpy change is the same for each route

Enthalpy cycle - diagram showing alternative routes between reactants and products

Hetero/homogeneous catalysts - homogeneous = same physical state from reactants, hetero = different physical state from reactants

Boltzmann distribution - distribution of energies of molecules at a particular temperature

Dynamic equilibrium - exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction

le Chatelier's principle - when a system in dynamic equilibrium is subjected to change, the position of equilibrium will shift to minimise the change

Greenhouse effect - process in which the adsorption and subsequent emission of infrared radiation by atmospheric gases warms the lower atmosphere and the planet's surface

Carbon capture and storage - removal of waste CO2 as a liquid injected deep in the oceans in underground porous rock

Stratosphere - second layer of the Earth's atmosphere, containing the 'ozone layer'

Adsorption - process that occurs when a gas, liquid or solute is held to the surface of a solid (or more rarely a liquid)