Lecture 3

Question 1

What is the relevance of shapes of molecules to pharmacy?

Answer 1

Receptors have specific shape that drug or drug inhibitors bind to
we get lock and key mechanism as shapes must compliment each other

Question 2

what does VSEPR stand for and what does it tell us

Answer 2

Valence shell electron pair repulsion theory
shape is determined by it and give us rules that help working out shapes of molecules

Question 3

what counts as 1 e- domain?

Answer 3

1 single bond, DB,TP or lone pair of e-
no of e- domains around central atom determine its shape

Question 4

rules of VSEPR

Answer 4

• atoms arrange themselves as far as possible to minimise repulsion
• lp repel more than BP
• no of e- domains around cental atom determine the shape

Question 5

What shape could molecules with 2 e- domains form

Answer 5

• linear
• bent

Question 6

what shape does co2 form

Answer 6

co2= 2BP 0LP so 2e- domains
linear shape
bonds arrange themselves as far as apart to minimise repulsion (in linear molecules thats 180)

Question 7

2 bp and 1lp shape and give example+ bond angle

Answer 7

3 e- domains
- bent shape as lp repel more than bp
- bond angle= 104
- e.g water

Question 8

why do LP repel more than BP?

Answer 8

they are freer and more spread

Question 9

why do multiple bond e- domains repel more than single bonds?

Answer 9

they have more e- so repel more= reduce bond angle more

Question 10

what shape do 1lp + 3 BP form?

Answer 10

• 4 e- domains
• 1 lp repels bp bond angle reduced from 109
• bond angle= 107

Question 11

trigonal bipyramidal shapes
draw+ label 2 types of bonds
give bond angle

Answer 11

e.g PCl5
- 5 e- domains
- axial and equatorial
- bond angles= 120 and 90
ax-ax = 180
ax-eq = 90
eq-eq= 120

Question 12

shapes with 6 e- domains

Answer 12

e.g SF6
- octahedral
- 90