Structure of materials

Question 1

What do the properties in solid materials depend on?

Answer 1

How the particles are arranged and held together

Question 2

The stronger the forces between the particles, the more “…” is needed to break the particles out of the solid structure?

Answer 2

Energy

Question 3

The more energy that is needed, the “…” the melting point of the solid.

Answer 3

Higher

Question 4

Many polymers, such as poly(ethene), contain long molecules that lie side by side.
Does this make the material flexible/inflexible?

Answer 4

The molecules can uncoil and slide past each other, making the material flexible.

Question 5

Do long polymer chains have stronger or weaker forces of attraction than shorter ones?

Answer 5

Stonger, producing a less flexible material

Question 6

What are ‘plasticisers’?

Answer 6

Small molecules that can be added to polymers during their manufacture

Question 7

What do ‘plasticisers’ do?

Answer 7

Push the polymer molecules slightly further apart, weakening the forces between them and making the material softer and more flexible

Question 8

What do ‘cross-links’ do?

Answer 8

Link together the chains of some polymers, making the material tougher and less flexible

Question 9

What is LDPE and HDPE?

Answer 9

Low-density polyethene and high-density polyethene

Question 10

What do polymer molecules that have side branches (LDPE) mean the structure is NOT?

Answer 10

Crystalline

The material is also less strong with a lower melting point

Question 11

What do polymer molecules that line up reguarly (HDPE) mean the structure IS?

Answer 11

Crystalline

The material is also stronger with a higher melting point