Chapter 13 Flashcards
Are alkenes saturated or unsaturated hydrocarbons?
Alkenes are unsaturated hydrocarbons
What shape and bond angles do each carbon in an alkene have?
Alkenes have a trigonal planar shape as they have three pairs of bonding electrons (double bonds count as one) and due to the equal repulsion of each pair 120 degree bond angles
What type of bonds do alkenes contain? Draw a diagram
Alkenes contain both sigma bonds due to the overlap of s orbitals and pie bonds due to the overlap of p orbitals
Are alkenes ridgid? Why/why not?
They are ridgid because the pie bonds locks the carbon atoms and stops them rotating around the double bond
Give the definition stereoisomers
Stereoisomers are compounds with the same structural formula but a different arrangement in space
What is needed for stereoisomerism to occur?
Restricted rotation due to the double bond and each double bonded carbon group must have two different atoms/ groups attached
What is E/Z isomerism?
A type of stereoisomerism in which the ‘e’ isomer has same groups are on opposite sides and ‘z’ isomer has the same groups on the same side
What is the Cahn Ingold Prelog rule?
The Cahn Ingold rule helps us to determine the E and Z isomers when there are 3 or 4 different groups attached to the double bonded carbons. Starting from the atom directly bonded to the carbon the higher atomic number takes priority.
What is cis/ trans isomerism?
A special case of stereoisomerism where one group atatched to each carbon is the same. The cis is the ‘z’ isomer and the trans is the ‘e’ isomer
Are alkenes more or less reactive than alkanes?
Alkenes are much more reactive due to the pie bond which can readily break ore easily as it has a lower bond enthalpy than sigma bonds.
Draw the electrophilic addition of ethene and hydrogen and state the conditions needed
Conditions- nickel catalyst and a temperature of 150 degree
Check using sheet
Draw the electrophilic addition of ethene and bromine
Check using sheet
What is Markownikoffs rule?
Markownikoffs rule for unsymmetric alkenes tells you which product will be more abundant depending on whether the carbocation is primary (bonded to one carbon), secondary (bonded to two) or tertiary (three). The higher the more abundant it will be.
Draw the electrophilic addition of but-2-ene and HBr
Check using the sheet
What are the advantages and disadvantages of disposing of waste polymers through combustion?
The heat produced can be used to generate electricity however polymers containing chlorine (eg PVC) will produce HCl which is poisonous and must be removed
