Chapter 13

Carbons with double bonds are bonded to three other atoms There are 3 groups of electron densities Which repel as far away from each other as possible Giving the carbons a trigonal planar shape The bond angle around each carbon is 120

The direct overlap of orbitals of 2 adjacent bonded atoms, with the electron densities above and below the plane of the bonding atoms

Sigma Valence electrons are locked between the nuclei of c and the atom it bonds with Pi 1 Valence electron is allowed to move back and forth between the double bonded atoms Densities occupy greater space above and below the plane between the bonded atoms

Pi bonds electrons are not localised Outside of the double bond Easily intercepted Readily breaks and undergoes addition reactions

Pi bond locks the carbons together Prevent from rotating Because densities are above and below plane

Add bromine water drop wise Change from organe to clear - double bond is present

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

Cis - zame zide Trans - evade

Mix alkene with hydrogen Nickel catalyst 423k

Mix alkene with halogen Rt

Bubble gaseous hydrogen halide through alkene Rt

Mix alkene with steam Phosphoric acid catalyst

Atom/s that are attracted to an electron rich centre and accepts electron pairs

• the pi bond electrons are attracted to the partially positive hydrogen causing carbon double bond to break • sigma bond forms between hydrogen in H-Br and the carbon that was in the double bond • h-br breaks heterolytically - electron pair goes to Br • producing a br ion and positive carbocation • br ion reacts with carbocation

• Pi bond electrons polarise the br-br bond by repelling its electrons, making an induced dipole • Pi electrons are attracted to partially positive Br + end, causing carbon double bond to break • forming a sigma bond between the br and carbon • br - br bond breaks heterolyticalky with the electron pair going to the Br- end • producing a carbocation and br ion • they react to form the addition product of the reaction

The hydrogen halide that reacts with the most stable carbcation

The carbocation with the most alkyl groups attached Alkyl groups have an electron donating effect They push electrons towards the positive charge causing the positive charge to spread The more it spreads the more stable it is