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Flashcards in a level Alkenes Deck (18)
1

what is the nature of the double bond?

a sigma bond surrounded by a pi bond

2

what is a pi bond?

the overlap of two p orbitals

3

what shape are alkenes and why?

trigonal planar
3 regions of e- density around each c atom
all in the same plane

4

what are stereoisomers?

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

5

what conditions are required for E/Z isomerism?

a c=c double bond
different groups attached to each c of the double bond

6

what is cis-trans isomerism?

where one of the groups on each carbon is hydrogen

7

what is the Cahn-Inglod-Prelog rule?

what distinguishes E/Z isomers

8

how do you determine an atoms priority?

highest atomic no.

9

why are alkenes relatively reactive?

the pi bond breaks easily

10

why does the pi bond break easily?

bond enthalpy is weaker

11

what addition reactions do alkenes undergo?

hydrogenation
halogenation
hydrogen halides
steam

12

what conditions for hydrogenation?

423K and nickel catalyst

13

what conditions for halogenation?

none but adding bromine water tests for unsaturation

14

what conditions for the addition of hydrogen halides?

room temperature

15

what conditions for hydration?

phosphoric acid catalyst

16

why does electrophilic addition occur?

the double bond is an area of high e- density
this attracts electrophiles

17

what is an electrophile?

a small molecule that accepts an electron pair and is added across the double bond

18

what is the electrophilic mechanism?

the positive dipole is attra