resonance introduction

Question 1

properties of benzene?

Answer 1

planar molecule
six identical carbon-carbon bonds
each pie electron shared by all carbons
pie electyrons are delocalised

Question 2

difference between localised and delocalised electrons?

Answer 2

in resonance contributors the electrons are localised
in resonance hybrid the electrons are delocalised

Question 3

rules for resonance?

Answer 3

only the electrons move
Only pie electrons and lone-pair electrons move
The total number of electrons in the molecule does not change
The numbers of paired and unpaired electrons do not change

Question 4

how are resonance contributors obtained?

Answer 4

by moving pie electron towards positive charge

Question 5

rule for movement of electrons to sp2 and sp3

Answer 5

electron always move towards an sp2 carbon not to an sp3

Question 6

when are resonance contributors the least stable?

Answer 6

resonance contributors with separated charges are less stable

Question 7

difference between resonance contributor and resonance hybrid?

Answer 7

resonance contributor is imaginary but resonance hybrid is real

Question 8

rules for moving electrons?

Answer 8

Move p electrons toward a positive charge or toward a p bond
Move lone-pair electrons toward a p bond
Move a single nonbonding electron toward a p bond

Question 9

how are resonance contributors obtained?

Answer 9

moving electrons from pie bond to positive charge

Question 10

how is alanine resonance structure drawn?

Question 11

what happens to electrons when resonance contributors are formed?

Answer 11

not removed or added from a molecule

Question 12

why is the movement of electrons away from more electronegative atom better than no movement at all?

Answer 12

because electron delocalization makes a molecule more stable

Question 13

what decreases the stability of a resonance structure?

Answer 13

An atom with an incomplete octet
A negative charge that is not on the most electronegative atom
A positive charge that is not on the most
electropositive atom
charge separation

Question 14

pattern between resonance contributor and hybrid?

Answer 14

The more stable a resonance contributor is, the more it contributes to the resonance hybrid

Question 15

relationship between stability of resonance contributors and resonance energy?

Answer 15

the more the number of relatively stable resonance contributors, the more the resonance energy
the more nearly equal resonance contributors are the more the resonance energy