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addition reaction - an organic reaction in which two reactant molecules combine to give a single product molecule.

bitumen – a fraction of crude oil consisting of hydrocarbon chains with 40+ carbon atoms. Also known as tar and used in road surfacing and in roofing.

cis–trans isomerism - a category of stereoisomerism in alkenes in which groups are attached to the carbon atoms involved in the double bond in a different way. In cis isomers, the groups are on the same side of the double bond, whereas in trans isomers, the groups are on opposite sides. Also known as geometric isomerism.

catalytic cracking – the bonds are broken using a high temperature (450oC, which is generally lower than in thermal cracking), a slight pressure (slightly greater than 1 atmosphere), and a zeolite catalyst.

chain isomers – a category of structural isomerism in which molecules have the same molecular formula but have a different arrangement of the carbon chain.
Chain isomers belong to the same homologous series. For example, 3-methylpentane and 2,3-dimethylbutane are both chain isomers of hexane.

complete combustion – the combustion of hydrocarbons to produce carbon dioxide and water

diesel or gas oil – used for truck, central heating fuel.

displayed formula – a chemical formula showing the arrangement of atoms and bonds in a molecule.

elimination reactions – removal of small molecule such as H2O, from an organic molecule.

E–Z isomerism - a system of notation used for complex stereoisomers that cannot be identified as either cis or trans isomers.

empirical formula – a chemical formula showing the simplest ratio of atoms present in a molecule. For example, the empirical formula of hexane is C3H7

free radicals – the species produced when a bond breaks homolytically functional group. An atom or group of atoms present in a molecule that is responsible for its characteristic chemical properties.

gasoline – a fraction of crude oil consisting of hydrocarbon chains with 5–10 carbon atoms. Also known as petrol and mainly used as a fuel for internal combustion engines.

general formula – a chemical formula used to calculate the molecular formula of any member of a homologous series. For example, the general formula for alkanes is CnH2n+2. The general formula of a specific alkane can be calculated by substituting n with the number of carbon atoms it contains.

hydrocarbon – a compound made up of carbon and hydrogen only.

homologous series – a group of compounds that all have the same functional group but a different number of carbon atoms. Examples include alkanes, alkenes, alcohols, amines, and halogenoalkanes.

incomplete combustion – if oxygen is not present in sufficiently large quantities, carbon monoxide or carbon is produced instead of carbon dioxide:
C4H10 + 2Β½O2β†’4C + 5H2O or
C4H10 + 4Β½O2 β†’4CO + 5H2O

initiation step – the first step in the mechanism of free radical substitution of alkanes by halogens. It involves the breaking of the halogen–halogen bond by UV light from the sun

isomerism – the existence of molecules that have the same molecular formula but a different arrangement of at-oms. Two broad cat-egories are struc-tural isomerism and stereoisomerism.

isomerism – a category of structural isomerism in which molecules have the same molecular formula but contain different functional groups and so belong to different homologous series. For example, both propanol (an alcohol) and methoxyethane (an ether) have the molecular formula C3H8O but contain different functional groups.

kerosene – a fraction of crude oil consisting of hydrocarbon chains with 11–16 carbon atoms. Used as a fuel for jet aircraft and as a feedstock for the chemical industry.

liquefied petroleum gas – gas for camping/ cooking with number of hydrocarbons 1-4

nucleophile – species that can act as a donor of a pair of electrons.

molecular formula – a chemical formula showing the actual number of each type of atom in a molecule. For example, the molecular formula of hexane is C6H14

optical isomerism – a category of stereoisomerism,in which two molecules are non-superimposable, mirror images of each other, a feature known as chirality. Optical isomers are also known as enantiomers.

organic – compounds that contain carbon atoms, which are usually bonded together to form chains or rings.

petrol or gasoline – fuel for cars

positional isomerism – a category of structural isomerism in which molecules have the same molecular formula but in which the functional group is attached to a different carbon atom. Positional isomers belong to the same homologous series.

propagation step – a step in a free-radical mechanism in which the radicals formed can then attack reactant molecules generating more free-radicals, and so on.

saturated hydrocarbons – compounds of hydrogen and carbon only in which the carbon–carbon bonds are all single covalent bonds, resulting in the maximum number of hydrogen atoms in their molecules.

substitution reaction – a reaction that involves the replacement of one atom, or group of atoms, by another.

skeletal formula – a chemical formula showing the bonds between carbon atoms but, unlike in a displayed formula, the carbon and hydrogen atoms are not shown.

stereoisomerism – a category of isomerism in which molecules have the same molecular formula but a different 3D arrangement of atoms. Two types are cis-trans isomerism and optical isomerism.

structural isomerism – a category of isomerism in which molecules have the same molecular formula but a different structural formula. Three types are chain isomerism, positional isomerism and functional group isomerism.

structural formula – a chemical formula showing how the atoms are arranged in a molecule and, in particular, showing what functional groups are present. Unlike in a displayed formula, single bonds are not shown, but multiple bonds may be shown. For example, the structural formula of propane is CH3CH2CH3, and propene is CH3CH2=CH2

termination step – two free radicals reacting together will form a molecule, with no free radicals generated.

thermal cracking – the bonds are broken using a high temperature (400-900oC) and a high pressure (70 atmospheres).