Shapes of molecules and intermolecular forces

Question 1

What is the electron pair repulsion theory?

Answer 1

• The electron pairs surrounding a central atom determine the shape of the molecule
• The electron pairs repel one another so that they are arranged as far as possible
• The arrangement of electron pairs minimises repulsion
• Different number of electron pairs result in different shapes

Question 2

What is bonding like in lone pairs?

Answer 2

• Repel more strongly than bonded pairs
• The bond angle is reduced by about 2.5 for each lone pair

Question 3

How many bonding pairs are in a tetrahedral and what is the bond angle?

Answer 3

4 bonding pairs
109.5 degrees

Question 4

How many bonding pairs are in a pyramidal and what is the bond angle?

Answer 4

3 bonding pairs and 1 lone pair
107 degrees

Question 5

How many bonding pairs are in a non-linear shape and what is the bond angle?

Answer 5

2 bonding pairs and 2 lone pairs
104.5 degrees

Question 6

How many bonding pairs are in a trigonal planar? and what is the bond angle?

Answer 6

3 bonding pairs
120 degrees

Question 7

How many bonding pairs are in a octahedral and what is the bond angle?

Answer 7

6 bonding pairs
90 degrees

Question 8

What shape is CO32- and NO3- and how many double bonds do they have?

Answer 8

Trigonal planar
1 double bond

Question 9

What does it mean if a molecule is symmetrical?

Answer 9

Non polar

Question 10

Why is non symmetrical molecule polar?

Answer 10

Because the dipoles do not cancel out

Question 10

Why is non symmetrical molecule polar?

Answer 10

Because the dipoles do not cancel out