2.2 How Structure Influences the Properties and Uses of Substances

Question 1

What properties do ionic compounds have?

Answer 1

• High melting points and high boiling points due to strong forces of attraction
• Dissolve easily in water
• Carry electric current if dissolved in water or melted

Question 2

What properties do simple molecular compounds have?

Answer 2

• Low boiling and melting point due to the weak intermolecular forces
  
  • The intermolecular forces are overcome, NOT the covalent bonds
• Gases or liquids at room temperature
• Don’t conduct electricity

Question 3

What structure do giant covalent compounds have?

Answer 3

• All the atoms are bonded by strong covalent bonds

Question 4

What’s the structure of diamonds?

Answer 4

Each carbon atom forms 4 covalent bonds with 4 other carbon atoms

Question 5

What’s the structure of graphite?

Answer 5

• Each carbon atom forms 3 bonds with 3 other carbon atoms, forming layers.
• The layers are free to slide over each other because there are no covalent bonds between the layers
• Graphite is soft and slippery
• 1 electron from each atom is free so it conducts heat and electricity

Question 6

What is nitinol?

Answer 6

A shape memory alloy. When it’s heated it returns to its original shape. It’s used in glasses and dental braces

Question 7

• How are LD polymers made?
• What are there properties?
• What are they used for?

Answer 7

• High temperature and pressure
• Flexible
• Bags and bottles

Question 8

How are HD polymers made?

What are there properties?

What are they used for?

Answer 8

• Lower temperature and pressure, with a catalyst
• Rigid
• Water tanks and drainpipes

Question 9

What are the properties of thermosoftening polymers?

Answer 9

• Individual tangled chains held together by weak intermolecular forces
• Melt easily and harden into a new shape when it cools

Question 10

What are the properties of thermosetting polymers?

Answer 10

• Strong intermolecular forces aand crosslinks that hold the chains together
• Strong, hard and rigid, doesn’t soften when heated

Question 11

How big are nanoparticles?

Answer 11

1-100 nanometres

Question 12

What are some uses of nanoparticles?

Answer 12

• Industrial catalyts
• Stronger, lighter building materials
• Cosmetics
• Nanomedicine
• Lubricant coatings
• Computer parts

Question 13

What are fullerenes?

Answer 13

Nanoparticles made of carbon shaped like hollow balls

Question 14

What are nanotubes?

Answer 14

Fullerenes that are joined together to make tubes a few nanometres across. They’re very strong