C2.3 Properties Of Materials

Question 1

What are allotropes

Answer 1

Different forms of elements in the same state but different atomic arrangements

Question 2

Give 2 examples of allotropes of carbon

Answer 2

Diamond and graphite

Question 3

Give 2 differences between Diamond and Graphite

Answer 3

Diamond is transparent and very hard

Graphite is Grey-Black and soft

Question 4

Describe the structure of diamond

Answer 4

Layers of carbon atoms held together by strong covalent bonds to form a lattice/regular structure

Question 5

Describe the structure of graphite

Answer 5

Layers of Carbon atoms held together by strong covalent bonds to form a lattice/regular structure.
Able to conduct electricity due to the delocalised electrons being able to flow around freely

Question 6

What is graphene?

Answer 6

A carbon allotrope that resembles a single layer of graphite.

Question 7

Describe graphene

Answer 7

Almost transparent
Extremely strong
Conducts electricity

Question 8

What do fullerenes form?

Answer 8

A large family of carbon allotropes

The molecules are shaped like tubes or balls

Question 9

What does a nanotube resemble?

Answer 9

a sheet of graphene rolled into a tube

Question 10

What are nanotubes used for?

Answer 10

They are strong and used to reinforce some sports equipment.

Question 11

What does a buckyball resemble?

Answer 11

a sheet of graphene closed to make a hollow ball.

carbon atomsmay be in pentagons as well as hexagons.

Question 12

Uses of Buckyballs

Answer 12

Lubricants, with molecules acting like tiny ball bearings

Question 13

Which 3 types of substance are usually solid at RT?

Answer 13

Metals
Ionic compounds
Giant Covalent

Question 14

Which type of substance is NOT solid at RT?

Answer 14

-Simple molecular substances
-usually in liquid or gas state at RT
or
-solid but easily melted

Question 15

What is sublimation?

Answer 15

When a solid becomes a gas straight away without becoming a liquid

Question 16

Why are some substance brittle? - GCS

Answer 16

• Giant Covalent structures contain many atoms held together in a lattice by strong covalent bonds.
• If a large enough force is applied, many covalent bonds break at once

Question 17

Why are some substances brittle? - Ionic compounds

Answer 17

Oppositely charged ions are held together in a lattice by strong ionic bonds.
If large enough force is applied, many ionic bonds break at once

Question 18

Which 2 types of substances are brittle?

Answer 18

• Ionic compounds

- Giant covalent structures

Question 19

Why do metals conduct electricity?

Answer 19

their delocalised electrons are free to move throughout the lattice

Question 20

Why don’t simple molecules or giant covalent structures conduct electricity

Answer 20

they do not have any delocalised electrons

Question 21

When do ionic compounds conduct electricity? Why?

Answer 21

In molten or in solution

the ions are free to move in the liquid state or when dissolved in a solvent

Question 22

What is a metalloid

Answer 22

An element that has properties for both metals and non-metals.

Question 23

What is a nanoparticle

Answer 23

• A particle between 1 nm and 100 nm across and consists of just a few hundred atoms

Question 24

what is a nanoparticulate?

Answer 24

a material made from nanoparticles

Question 25

Uses of nanoparticles

Answer 25

• New paints
• New cosmetics
• New medicine
• New sunscreens

Question 26

What are properties of nanoparticles due to?

Answer 26

Large surface area to volume ratio compared with the same substance in bulk

Question 27

Developments of nanoparticles:

Answer 27

• New catalysts to speed industrial reactions

- Self-cleaning windows, ovens, clothes

Question 28

Risks of Nanoparticles

Answer 28

• So tiny that they may be breathed in, absorbed by
  skin or pass into cells
  -Take a long time to break down once released into
  environment
• Toxic substances might stick to their surfaces
• May be harmful to human health