ORGANIC CHEM - ISOMERISM

a molecule with the same molecular formula but the atoms are arranged differently

isomers in which the atoms are connected in different ways

isomers with the same structural formula but a different arrangement of atoms in space

• chain isomers (caused by having a diff carbon chain (eg: butane and methylpropane)) • position isomerism (caused by the functional group being in a different position (eg: propan-1-ol and propan-2-ol)) • functional group isomerism (caused by having a different functional group (eg: cyclohexane and hex-1-ene))

• E-Z isomers/geometric isomers (caused by molecules with a C=C bond with 2 different groups attached to each of the C atoms in the C=C bond) • optical isomers (caused by C atoms having 4 different groups attached leading to molecules that are superimposable mirror images of each other)

no rotation in alkenes due to C=C double bond which causes geometric isomerism

• rules that allow us to figure out how to assign priority in order to decide if a molecule is an E isomer or a Z isomer • look at atoms directly bonded to each of the C atoms • higher atomic no. = higher priority • if higher priority groups are on the same side its a Z isomer • if higher priority groups are across from each other its an E isomer

a type of stereoisomerism that occurs when there is a carbon with 4 different groups bonded to it

the presence of a chiral centre leads to the presence of two possible isomers that are mirror images of each other

• plane polarised light • rotate polarised light in opposite direction

a 50:50 mixture of two enantiomers/optical isomers

• C=O bond is planar • nucleophiles are able to attack a molecule with a carbonyl group from above or below C=O bond • this means the two possible products of the reaction are mirror images and therefore optical isomers