1.3 Bonding Part 2

Question 1

Define electronegativity

Answer 1

The power of an atom to attract the pair of electrons in a covalent bond

Question 2

What happens to electronegativity value across a period? Why?

Answer 2

Increases because there is a smaller distance and a higher nuclear charge

Question 3

What happens to the electronegativity value down a group? Why?

Answer 3

Decreases because the bonded electrons are further from the nucleus and have more shielding

Question 4

What is the most electronegative atom?

Answer 4

Fluorine

Question 5

Why do noble gases not have electronegativity values?

Answer 5

They don’t normally form covalent bonds

Question 6

Is the molecule C-F polar? If yes show the partial charges

Answer 6

Yes
C - delta positive
F - delta negative

Question 7

Is the molecule C-H polar? If yes show the partial charges

Answer 7

No

Question 8

Is the molecule N-H polar? If yes show the partial charges

Answer 8

Yes
N - delta negative
H - delta positive

Question 9

Is the molecule O-H polar? If yes show the partial charges

Answer 9

Yes
O - delta negative
H - delta positive

Question 10

Is CO2 polar?

Answer 10

• It has polar bonds
• Non-polar molecule
• molecule is symmetrical so the dipoles cancel

Question 11

Is H2O polar?

Answer 11

Yes
Polar bonds
Polar molecule

Question 12

What are the three types of intermolecular force?

Answer 12

• Van Der Waals
• Permanent dipole-dipole
• Hydrogen bonds

Question 13

What causes Van Der Waals forces?

Answer 13

The movement of electrons which unbalanced the charge distribution within the molecule

Question 14

What is a Van Der Waals force and how does it form?

Answer 14

• electrons move which unbalanced the charge distribution
• This creates an instantaneous dipole across the molecule
• This induces a dipole in neighbouring molecules
• Resulting in weak forces of attraction

Question 15

Do bigger molecules have greater or weaker Van Der Waals forces?

Answer 15

Stronger

More electrons

Question 16

Draw and describe the intermolecular force formed from two HCl molecules joining

Answer 16

Permanent dipole-dipole
H - delta pos
Cl - delta neg
Hydrogen joins with chlorine

Question 17

Between what does hydrogen bonding occur?

Answer 17

N-H
O-H
F-H

Question 18

What happens when a gas turns into a solid?

Answer 18

Deposition

Question 19

What happens when a solid turns into a gas?

Answer 19

Sublimation

Question 20

When can an electric current flow?

Answer 20

When charged particles are free to move

Question 21

What can carry a current?

Answer 21

Delocalised electrons or free ions

Question 22

What can ionic and polar substances dissolve in?

Answer 22

Polar solvents

Question 23

What can non polar substances dissolve in?

Answer 23

Non polar solvents

Question 24

What is a giant ionic lattice belt together by?

Answer 24

The electrostatic attraction between the oppositely charged ions

Question 25

Why do ionic compounds have high melting points?

Answer 25

The ions are held together by strong ionic bonds which need a lot of energy to break

Question 26

Do ionic compounds conduct electricity when solid with reason

Answer 26

No | The ions are not free to move so cannot carry the current

Question 27

Do ionic compounds conduct electricity when dissolved or molten with reason

Answer 27

Yes | The ions are free to move so can carry the current

Question 28

Why are ionic compounds brittle?

Answer 28

* If enough force is applied the layers slide over each other * Like charges will move next to each other, causing repulsion and the lattice structure breaks down

Question 29

Why do metals have high melting points?

Answer 29

Metallic bonds are strong, so a large amount of energy is needed to break them

Question 30

Why do metals conduct electricity?

Answer 30

Because the delocalised electrons can flow through the structure and carry the current

Question 31

Why are metals strong?

Answer 31

* Metallic bonds are strong and extend through the giant metallic lattice * Metallic bond strength depends on the size and charge of the metal ion

Question 32

Why are metals malleable and ductile?

Answer 32

The layers of ions in the giant ionic lattice can slide over each other into new positions, without disrupting the metallic bond

Question 33

What are the two types of covalent substance?

Answer 33

* Simple molecular covalent | * Macromolecular covalent

Question 34

Why do covalent substances have low melting points?

Answer 34

The forces of attraction between the molecules are weak | Not much energy is needed to break them

Question 35

Are covalent substances soluble?

Answer 35

Generally insoluble in water, unless they can form hydrogen bonds or react with water

Question 36

Can covalent substances conduct electricity?

Answer 36

No | They don't contain ions or delocalised electrons