Alkenes and polymers

Unsaturated hydrocarbons Double c=c bond

CnH2n

Molecule made of carbon and hydrogen atoms only

Restricted rotation around c=c (Double bond)

Look going vertically look for priority group (w highest atomic number) on each side Then going horizontally if priority group on same side ( Z isomer) if on different side (E isomer)

Adding alkene to bromine water makes it turn from orange to colourless.

Planar 120-121 degrees

One sigma bond One pi bond

Same structural formula different arrangement of atoms in space

Sideways overlap of p orbitals

Sigma bonds are stronger

No sig difference in alkenes and alkanes based on mp and bp Only vdw forces present Both insoluble in water (cannot form h bonds w it) Non polar

Prod co2 and H2O Not typically used as fuels instead used in chemical reactions

Ethene + bromine —> 1.2 di bromo ethane

Although c=c bond has lower bond Enthalpy it’s more reactive due to double bind creating an area of high electron density Thus susceptible from attack by an electrophille

Electron pair acceptor It’s an electron deficient species thag attacks and is attracted to areas of high electron density They add across double bond bc it’s unsaturated

Electrophilic addition

Occurs due to heterolutic fission Non polar br2 approches c=c one br atom gets delta pos charge and other gets delta negative Arrow from doube bind to delta positive br then from middle of thag bonf to delta neg br cus it takes binfing pair of e Forms one new c - br and carbon cation Then arrow from lone pair on br to carbon cation on alkane (double bond broken) then making haloalkane

C=C is an area of high electron density Br2 becomes polarised/induced dipole Delta postive br attracted to C=C

Br2 Hbr (hydrogen bromide) H2SO4 (sulphuric acid) And reaction w steam

tertirary secondary primary

major and minor product

an ion with positivly charged carbon atom

addititon condensation