Alkenes

Question 1

What is a sigma bond ?

Answer 1

The end to end overlapping of orbitals in a bond

Question 2

What is a Pi bond?

Answer 2

The lateral overlap of electrons in the p sub shell. Pi bonds extend above and below the plane of the bonding atoms

Question 3

What is the test and result for Alkenes ?

Answer 3

Bromine water test. Colourless if alkene is present. Stays orange if not

Question 4

Define electrophile

Answer 4

Electron pair acceptors. Attracted to ares of high electron density e.g. c=c.

Question 5

What is the general formula for an alkene ?

Answer 5

CnH2n

Question 6

Draw a c=c with sigma and Pi bonds

Answer 6

Pi
C obond C
Pi

Question 7

Define stereoisomerism

Answer 7

Molecules that have the same structural formula but different spatial arrangement of atoms

Question 8

Why does E/Z isomerism not occur in alkanes ?

Answer 8

Single bonds are able to rotate as there are no Pi bonds and so can change their spatial arrangement without changing structural. The c=c in alkenes has restricted rotation and so spatial arrangement cannot change

Question 9

What is E isomerism ?

Answer 9

Higher priority functional groups are opposite to each other on the double bond

Question 10

What is Z Isomerism ?

Answer 10

Bonds of the same functional priority are on the same side of the double bond

Question 11

What are the priority rules for E/Z isomerism ?

Answer 11

-Directly bonded atom with the highest number of electrons has highest priority
- move to the next atom if a draw
- atom with the highest number of bonds

Question 12

What is cos/trans isomerism?

Answer 12

A different way of naming isomerism but other is preferred.
Cis = same side
Trans = opposite