Chapter 6- Shapes of Molecules and Intermolecular forces

Question 1

What does a dotted wedge mean when drawing displayed formulae of compounds?

Answer 1

A bond going into the plane of the paper

Question 2

What does a solid wedge mean when drawing displayed formulae of compounds?

Answer 2

A bond coming out of the plane of the paper

Question 3

Why does a lone pair repel more that bonded pairs?

Answer 3

Slightly closer to the central atom, and occupies more space than a bonded pair.

Question 4

What is the name and bond angle for a molecule with 4 bonded pairs and no lone pairs?

Answer 4

Tetrahedral, 109.5

Question 5

What is the name and bond angle for a molecule with 3 bonded pairs and 1 lone pairs?

Answer 5

Trigonal pyramidal, 107

Question 6

What is the name and bond angle for a molecule with 2 bonded pairs and 2 lone pairs?

Answer 6

Non- linear, 104.5

Question 7

What is the name and bond angle for a molecule with 2 bonded pairs and no lone pairs?

Answer 7

Linear, 180

Question 8

How many bonded pairs does a double covalent bond count as?

Answer 8

1

Question 9

What is the name and bond angle for a molecule with 3 bonded pairs and no lone pairs?

Answer 9

Trigonal planar, 120

Question 10

What is the name and bond angle for a molecule with 6 bonded pairs and no lone pairs?

Answer 10

Octahedral, 90

Question 11

Define Electronegativity

Answer 11

The attraction of a bonded atom for the pair of electrons in a covalent bond

Question 12

How is electronegativity measured?

Answer 12

Using the Pauling scale

Question 13

When will a molecule be non-polar?

Answer 13

The bonded atoms are the same OR the bonded atoms have the same or similar electronegativity values

Question 14

What is the separation of opposite charges known as?

Answer 14

A dipole

Question 15

Does Carbon dioxide have a dipole?

Answer 15

No, as the molecule is symmetrical

Question 16

Describe London Forces (Induced dipole-dipole interactions.)

Answer 16

Weak intermolecular forces that exist between all molecules, polar or non-polar .

Question 17

What are permanent dipole-permanent dipole interactions?

Answer 17

Intermolecular force between the slightly positive end of on molecule and the slightly negative side of another molecule

Question 18

Which is stronger, London forces, or permanent dipole-permanent dipole interactions?

Answer 18

Permanent dipole-permanent dipole interactions

Question 19

What kind of bonding is present in HCl?

Answer 19

Permanent dipole-permanent dipole interactions and London forces

Question 20

What kind of bonding is present in Carbon dioxide?

Answer 20

London forces only

Question 21

What is Hydrogen bonding?

Answer 21

A special type of permanent dipole-permanent dipole interaction found between a Hydrogen with a Oxygen, Nitrogen or Fluorine

Question 22

Which intermolecular force is strongest?

Answer 22

Hydrogen bonding

Question 23

Why is ice less dense than water?

Answer 23

Hydrogen bonding holds water molecules apart in poen lattice structure
The water molecules in ice are further apart than in water
This makes ice less dense and so floats in water.

Question 24

Why does water have a relatively high melting point and boiling point?

Answer 24

Each water molecule makes 4 Hydrogen bonds which require a lot of energy to break so water has a higher boiling point and melting point than expected.