2 Bonding 2

Question 1

State the melting points of ionic substances

Answer 1

High

Question 2

Explain why ionic substances have high melting points.

Answer 2

Strong bonds between oppositely charged ions are hard to break

Question 3

Will NaCl(s) conduct electricity?

Answer 3

No

Question 4

Will NaCl (aq) conduct electricity?

Answer 4

Yes (aq stands for aqueous which means it is dissolved in water)

Question 5

Will NaCl (l) conduct electricity?

Answer 5

Yes

Question 6

What does molten mean?

Answer 6

Melted

Question 7

Explain why ionic compounds do not conduct electricity when solid

Answer 7

Because the ions are not free to move

Question 8

Explain why ionic compounds conduct electricity in solution

Answer 8

Because the ions are free to move

Question 9

Explain why ionic compounds conduct electricity when molten

Answer 9

Because the ions are free to move

Question 10

What does soluble mean?

Answer 10

Dissolves in water

Question 11

What does insoluble mean?

Answer 11

Does not dissolve in water

Question 12

Magnesium carbonate is insoluble. What do you need to do before it will conduct electricity?

Answer 12

Melt it

Question 13

Sodium fluoride is soluble. Explain what the easiest way for it to conduct electricity is

Answer 13

Dissolve it in water because this does not require high temperatures

Question 14

Explain why chlorine and fluorine form covalent bonds

Answer 14

They are both non-metals

Question 15

Complete the sentence: In covalent bonds, electrons are _______________________

Answer 15

Shared

Question 16

In ionic bonds, electrons are ___________________

Answer 16

Transferred

Question 17

What is the name given to the structure of diamond, graphite and silicon dioxide?

Answer 17

Giant covalent

Question 18

How many bonds does each carbon have in diamond?

Answer 18

4

Question 19

Explain why diamond has a high melting point

Answer 19

Giant structure, Strong covalent bonds between the atoms, requires a lot of energy to break

Question 20

Explain why most giant covalent substances do not conduct electricity (3 marks)

Answer 20

There are no electrons/ions/charged particles that are free to move

Question 21

Explain why graphite conducts electricity

Answer 21

Has delocalised electrons between the layers that can move through the graphite

Question 22

Explain why graphite can act as a lubricant

Answer 22

Weak forces between layers which are free to slide over each other

Question 23

What is graphene?

Answer 23

One layer of graphite

Question 24

What is a fullerene?

Answer 24

Substance made of carbon atoms arranged in a cage

Question 25

What type of substance are methane and water?

Answer 25

Simple molecular (or simple molecules)

Question 26

What is a molecule?

Answer 26

A group of atoms chemically bonded together

Question 27

Describe the structure of simple covalent molecules

Answer 27

Strong covalent bonds between atoms, weak forces holding the molecules together

Question 28

What are intermolecular forces?

Answer 28

Weak forces between molecules which hold them together

Question 29

Explain why methane has a low melting point

Answer 29

It is a simple molecular substance with weak forces between the molecules (which are easy to break)

Question 30

What is a polymer?

Answer 30

Millions of small molecules joined together in a chain to form a large molecule