3.3.4.1 Structure bonding and reactivity (Alkenes) Flashcards
What are alkenes?
Unsaturated hydrocarbons (they have at least one C=C bond)
What are some other properties of alkenes?
Only weak VdW forces between molecules
Physical properties are very similar to alkanes
As the carbon chain increases, so does the m.p. and b.p.
Insoluble in water
Describe the structure of alkenes
The first bond is formed as a sigma bond, which can rotate. However, the second pi-bond is unable to rotate, and so enforces restricted rotation.
How is a pi-bond formed?
Through the overlap of p-orbitals
What is a sigma bond?
The single bond between two carbons.
Why are alkenes not used as fuels?
Their reactivity allows us to use them for other uses
Why are alkenes more reactive than alkanes?
Double bond can easily be attacked by electrophiles.
What are electrophiles?
Electron pair acceptors - they are electron deficient, so have either a positive or partially positive (delta+) charge e.g. H+
