TOPIC 3 - U1 - Materials

Question 1

2 Types of materials

Answer 1

Natural materials
Synthetic materials

Question 2

Def : Natural materials

Answer 2

Naturally occuring materials found in nature

Question 3

Def: Synthetic materials

Answer 3

Artificial or man-made materials from different chemicals added together

Question 4

Natural or Synthetic?
wood
metals
concrete
glass
plastic
ceramic

Answer 4

wood - N
metals - N
concrete - S
glass - S
plastic - S
ceramic - S

Question 5

Fibres classified as

Answer 5

Natural / synthetic

Question 6

3 Natural plant fibres

Answer 6

cotton, flax, sisal

Question 7

2 Natural animal fibres

Answer 7

wool, mohair

Question 8

Uses for natural fibres

Answer 8

used to spin into threads that are then woven or knit into textiles

Question 9

Uses for synthetic fibres

Answer 9

can be produced from which textiles can be woven or knitted

Question 10

3 Synthetic fibres

Answer 10

polyester, nylon, terylene

Question 11

How are composite materials made

Answer 11

by mixing 2 substances together like grass and dung, where grass is the reinforcement + dung is the matrix

Question 12

Explain reinforced concrete in context to composite materials

Answer 12

concrete is the matrix + steel bars are the reinforcement

Question 13

Explain fiberglass in context to composite materials

Answer 13

the tiny shards of glass are the reinforcement + they are held together by resin, the matrix

Question 14

Explain wood in context to composite materials

Answer 14

natural composite materials have cellulose fibres that are held together by lignin

Question 15

What type of bonds keep metals together and explain how metals are bonded

Answer 15

• They are held strongly together by metallic bonds.
• Metal atoms in a crystal have outer electrons that can move around freely between atoms. metals are made of rows of positive ions surrounded by a sea of moving electrons which are strongly attracted by positive ions.

Question 16

What type of bonding takes place between concrete

Answer 16

It has both ionic and covalent bonding

Question 17

What is concrete made from

Answer 17

a mixture of sand, gravel, cement and water

Question 18

Where does the long thin crystals that overlap in concrete come from and what is that material made of

Answer 18

it comes from the cement that’s part of the concrete.
cement is made of a mixture of calcium silicate and aluminium silicate

Question 19

Why does concrete shatter easily when hit with a hammer

Answer 19

Because the crystals in the concrete are ionically bonded and the sand is covalently bonded.

Question 20

How is glass made

Answer 20

by heating calcium carbonate with sodium carbonate and sand. they then melt together and forms liquid glass. it’s then cooled to form solid glass

Question 21

What is glass made of

Answer 21

non-crystalline solids

Question 22

Why is glass considered a liquid

Answer 22

it has a structure of a liquid, but behaves like a solid

Question 23

What type of bond holds glass together

Answer 23

covalent bonds which forms a giant covalent structue

Question 24

Def:
Giant covalent structures

Answer 24

when atoms form covalent bonds with neighboring atoms to create giant lattices

Question 25

What is a polymer

Answer 25

a large molecule made up of chains of repeating units of monomers

Question 26

2 Types of polymers

Answer 26

natural polymer - cellulose
synthetic polymer - plastic

Question 27

Cellulose is a natural polymer in wood. Explain the structure of cellulose

Answer 27

It’s a complicated structure containing atoms of C, H and O2. They are strong due to their electrostatic forces and covalent bonds. It cannot be stretched or broken, but can be bent. Held tightly together

Question 28

How is cellulose fiber made and what is its use

Answer 28

made when wood is crushed and it forms long thin pieces which is then used to manufacture paper

Question 29

What is plastic made of

Answer 29

fossil fuel sources like crude oil and natural gas

Question 30

How is plastic formed

Answer 30

from long chains of carbon atoms, together with other elements that are held together by strong covalent bonds

Question 31

Why is plastic a source of pollution

Answer 31

because it cannot decompose is the environment

Question 32

4 Types of plastic

Answer 32

polythene
nylon
melamine
polyurethane

Question 33

Why is it difficult to break polythene

Answer 33

molecules are held together strongly and molecules are lined in different directions which makes them flexable

Question 34

What is the use for polythene

Answer 34

to make shopping bags

Question 35

Why is nylon a strong material

Answer 35

The forces between the molecules are electrostatic. The molecules can slide next to each other making nylon very flexible

Question 36

What is nylon used for

Answer 36

making clothes, fishing lines and ropes

Question 37

What type of bond is between melamine molecules

Answer 37

covalent bonds between polymer

Question 38

Describe melamine

Answer 38

its very hard and rigid. melamine doesn’t break or melt easily

Question 39

What is melamine used for

Answer 39

making plastic surfaces for desks + manufacture plates and bowls

Question 40

How is polyurethane bonded together

Answer 40

joined together very loosely in a random way

Question 41

Describe polyurethane

Answer 41

plastic can be squashed or stretched without permanently changing its shape. It has weak forces and is not very strong. weak plastic

Question 42

What is polyurethane uses

Answer 42

to make foam mattresses