6th

Question 1

to predict how smt might react
or if they have reacted we should look at

Answer 1

movement of electrons

Question 2

what is a resonance arrow used for

Answer 2

shows the interconversion between 2 different representations of the same molecule

Question 3

if we draw an arrow from somewhere that place should then have

Answer 3

a positive charge

Question 4

if we draw an arrow to somewhere that place should have a

Answer 4

negative charge

Question 5

H+ number of electrons

Answer 5

0
this is a proton

Question 6

electrons can be shared from a lone pair or a

Answer 6

bond
arrow should be drawn through the C that is making the bond
the C would then have a +

Question 7

species giving the electrons is called a

Answer 7

nucleophile
attracted to positive

Question 8

species that receive the electrons

Answer 8

electrophile
attracted to the negative

Question 9

the higher the enthalpy of hydrogenation

Answer 9

the less stable it is
more energy released

energy released when smt is heated up

Question 10

when double bonds and single bonds alternate

Answer 10

conjugated alkenes

Question 11

what is a property of conjugated alkenes

Answer 11

they are more stable than expected
they release less energy than expected

Question 12

different between conjugated and non conjugated alkenes

Answer 12

conjugated: pi orbitals overlap and interact + overlap allowing greater stability

non conjugated: pi orbitals are not close enough to interact + overlap and increase stability

Question 13

how come they both have pi orbitals??

Answer 13

alkenes : sp2 hybridised meaning one 1 orbital is not hybridised and is free

Question 14

orbitals

Answer 14

regions of space where electrons are likely to be found

Question 15

nodes

Answer 15

areas of space where the probability of finding an electron is 0

points of 0 electron density

Question 16

the more conjugated a system is…

Answer 16

the less nodes there are
less nodes = lower energy
lower energy = more stable

Question 17

particle in the box

Answer 17

3 nodes = highest energy empty
2 nodes = LUMO - lowest unoccupied molecular orbital) empty
1 node = HOMO - highest occupied molecular orbital) full
0 nodes = lowest energy full

Question 18

in conjugated systems electrons can be

Answer 18

shared throughout 1 extended molecular orbital

FORMS RESONANCE STRUCTURES

Question 19

what do resonance structures help us understand

Answer 19

how organic molecules may react

Question 20

resonance can also be called the

Answer 20

mesomeric effect

Question 21

what is the mesomeric effect

Answer 21

electrons being moved within a molecule

can influence: acidity, basicity + movement of charge

effects the behaviour of molecules

Question 22

conjugated nucleophilic addition // michael addition

Answer 22

when u conjugate a molecule
u see it can react in a way u didn’t think it would before.
nucleophile attacking end carbon due to double bond electron density moving + leaving it with a + charge.

Question 23

conjugation can occur with bonds and

Answer 23

lone pairs!!!

Question 24

whats so great about benzene + conjugation

Answer 24

resonance in benzene leads to greater stability than in linear conjugated alkenes.

this is bc p orbitals involved in pi bonds are aligned perfectly for max conjugation

Question 25

what are the 4 conditions to making smt aromatic

Answer 25

• flat
• conjugated pi electrons
• cyclic
• HUCKELS RULE ( 4n+2 electron number)

Question 26

more on HUCKELS RULE
read this

Answer 26

benzene = 6 electrons
4n+2
if n= 1 the answer is 6
this means benzene fits it.

n is in integer that when combined with the equation, should give the total number of pi electrons in the molecule.

Question 27

difference between aromatic and non aromatic molecules

Answer 27

aromatic = much more stable

aromatic -> non aromatic = energy penalty

smt can react with non aromatic but will find it harder to react with aromatic as it’s far more stable.

Question 28

alkenes and aromatics are separate things!!

what goes between the two

Answer 28

conjugated alkenes

Question 29

what about aromatic molecules with electron donating groups bonded to it.
eg: phenol

Answer 29

lone pairs on the O can make the pi system more electron rich.

this attracts more electrophiles