IB Chemistry HL Topic 10 & 20

homologous series

- successive members of a homologous series differ by a -CH2 group
- members of HS can be represented by same general formula
- members of homologous show a gradation in their physical properties
- members of a series have similar chemical properties

functional group

small group of atoms attached to a carbon atom in a molecule, giving characteristic properties to the compound

chemical properties

illustrated by sections that follow on different homologous series

physical properties

result of changes that occur in the strength of Van der Waals' forces w/ increasing molar mass and in some cases a change in molecular polarity

condensed structural formula

bonds are omitted, side chains put in brackets and repeated identical groups collected together

molecular formula

gives actual number of each type of atom in molecule

empirical formula

simplest whole number ratio

isomer

different compounds that have the same molecular formula

structural isomer

atoms joined in different order so that they have different structural formulae

stereo isomer

order the atoms are joined together is the same, but the molecules have a different arrangement of atoms in space and hence different 3D shapes

alkane

IPUAC name: -ane
- low chemical reactivity
- substitution: halogenation

alkene

IUPAC name: -ene

alcohol

IUPAC name: -anol

amine

IUPAC name: -anamine

aldehyde

IUPAC name: -anal

ketone

IUPAC name: -anone

carboxylic acid

IUPAC name: -anoic acid

amide

IUPAC name: -anamide

ester

IUPAC name: -anoate

nitrile

IUPAC name: -anenitrile

saturated reactant

compounds which only contain single bonds

unsaturated reactant

compounds which contain double or triple bonds

electrophile

- electron-deficient species which is attracted to parts of molecules which are electron rich
- positive ions or have partial positive charge

nucleophile

- electron-rich species which is attracted to parts of molecules which are electron deficient
- nucleophilies have a lone pair of electrons and may also have a negative charge

combustion reaction

Complete combustion: C8H18 + O2 --> CO2 + H2O
Incomplete combustion: C8H18 + O2 --> CO + H2O + C + CO2
- these products w/ other minor products of hydrocarbon combustion and residue of lead compounds, are major sources of air pollution

addition reaction

- occurs when 2 reactants combine to form a single product
- characteristic of unsaturated compounds
- (i.e. C2H4 + Br2 --> C2H4Br2)

halogenation reaction

- occurs when one atom or group of atoms in a compound is replaced by a different atom or group
- characteristic of saturated compounds and aromatic compounds
- (i.e. CH4 + Cl2 --> CH3Cl + HCl)
- initiation, propagation, termination

elimination reaction

- occurs when a small molecule is lost from a larger compound
- usually results in the formation of a double or triple bond
- when H2O is the eliminated molecule -- reaction is dehydration
- (i.e. C2H5OH --> C2H4 +H2O)

addition-elimination reaction

- occurs when two reactants join together and in the process a small molecule is lost
- reaction occurs b/w a functional group in each reactant
- also known as -- condensation reaction
- (i.e. RNH2 + R'COOH --> R'COHNR + H2O)

nucleophilic substitution reaction (SN2)

- Primary halogenoalkanes: SN2 mechanism
--> one-step mechanism dependent on concentration of both halogenoalkane and hydroxide ion

nucleophilic substitution reaction (SN1)

- Tertiary halogenoalkanes: SN1 mechanism
--> two-step mechanism
--> 1st step: halogenoalkane ionizing by breaking its carbon-halogen bond heterolytically
--> 2nd step: carbocation intermediate is attacked by nucleophilie to form new bond

homolytic fission

when covalent bond breaks by splitting the shared pair of electrons b/w two products
- produces two free radical each w/ unpaired electron

heterolytic fission

- when a covalent bond breaks with both the shared electrons going to one of the products
- produces two oppositely charged ions