Zusammenfassung der Ressource
ALKENES
- definition
- unsaturated hydrocarbons
(CnH2n)
- have at least one C=C double covalent
bond
- sigma bonds
- formed when 2 s
orbitals overlap
- highest possible e-
density between the
2 bonded nuclei
- this is a single
covalent bond
- high e- density means
strong electrostatic
attraction between nuclei
and shared pair of e-s
(strongest covalent bond)
- high bond enthalpy
- pi bonds
- formed by the sideways
overlap of 2 p orbitals
- two parts - 'above'+'below'
molecular axis because of
dumb-bell shaped p orbitals
- e- density is spread out so weaker
electrostatic attraction and low bond
enthalpy
- reactivity
- C=C contains sigma and
pi bonds so highly
reactive
- 4 e- (high density) and pi bond sticks out
above and below the rest of the
molecule
- means pi bond is likely to be attacked by
electrophiles
- low bond enthalpy of pi bond
- means alkenes are good staring
points for making other organic
compounds and petrochemicals