13.1 properties of alkenes Flashcards
what is the general formula of alkenes?
CnH2n
what is the shape of alkenes?
trigonal planar
what bond angle do alkenes have?
120
what types of covalent bonds make up a double bond?
1 sigma and 1 pi bond
what is a pi bond?
sideways overlap of 2 p-orbitals, one from each carbon atoms
where is the pi- electron density concentrated?
above and below the line joining the nuclei of the bonding atoms
how many electrons do each atom contribute in a pi bond?
one
how many electrons do each atom contribute in a sigma bond?
one
state what is meant by the term unsaturated
compounds with one or more double or triple bonds
explain the different between a pi bond and a sigma bond
a sigma bond is the result of the head on overlap of orbitals
pi bond is formed from the sideways overlap of p- orbitals
explain why the bond angle around the carbon atom in an alkene is different to the bond angle around a carbon atom in an alkane
alkene:
- 3 bonding regions about the carbon atom
- these repel each other equally resulting in a trigonal planar shape
- bond angle 120
alkane:
- 4 bonding regions about the carbon atom
- these repel each other equally resulting in a tetrahedral shape
- bond angle 109.5
what does the pi bond restrict?
restricts rotation around the double bond
