Chapter 2 - Strucute And Properties

Question 1

Why do ionic compounds conduct electricity when melted into liquid or when dissolved in water

Answer 1

Because the ions are free to move. This allows them to carry electrical charge

Question 2

Why do some ionic solids dissolve in water

Answer 2

Because the water molecules can split up the lattice.

Question 3

Why do simple molecules have little attraction for each other

Answer 3

These bonds act only between the atoms within the molecule

Question 4

Do substances made of simple molecules have low or high melting and boiling points

Answer 4

Low

Question 5

Why do simple molecules not conduct electricity

Answer 5

Molecules have no overall charge and so cannot carry electrical charge

Question 6

What does intermolecular forces mean

Answer 6

The forces of attraction between molecules

Question 7

Why do substances made of simple molecules have low melting points and boiling points

Answer 7

There are weak intermolecular forces between simple molecules

Question 8

Why do giant covalent structures have very high melting points

Answer 8

Every atom in the structure is joined to several other atoms by strong covalent bonds. It takes an enormous amount of energy to break down the lattice and so substances have very high melting points

Question 9

What are two similarities between diamond and graphite

Answer 9

They are both a form of carbon.

The atoms are covalently bonded.

Question 10

What are two differences between diamond and graphite

Answer 10

Diamond has a regular three dimensional giant structure.
Graphite has the carbon atoms in giant flat two dimensional layers
There are no covalent bonds between the layers so they slide over each other

Question 11

Why does graphite conduct heat and electricity

Answer 11

One electron from each carbon atom is delocalised, delocalised electrons allow graphite to conduct heat and electricity

Question 12

What are some of the applications for fullerenes

Answer 12

• Drug delivery into the body
• Lubricants
• Catalysts
• Reinforcing materials

Question 13

Why do ionic compounds have high melting points and high boiling points

Answer 13

Ionic compounds are solids at room temperature so a lot of energy is needed to overcome the ionic bonds to melt the solids

Question 14

Why can the layers of graphite slide over each other quite easily

Answer 14

There are only weak intermolecular forces between the layers

Question 15

Why are metals useful for making wires, rods and sheet materials

Answer 15

Metal atoms are arranged in layers. When a force is applied the layers of atoms can slide over each other. They can move into a new position without breaking apart, so the metal bends or stretches into a new shape.

Question 16

What is an alloy

Answer 16

A mixture of metals or metals mixed with other elements

Question 17

Why are alloys harder than pure metals

Answer 17

The different sized atoms in the mixture distort the layers in the metal structure and make it more difficult for them to slide over each other.

Question 18

What happens when you hear a shape memory alloy

Answer 18

It returns to its original shape

Question 19

Why are shape memory alloys useful

Answer 19

They can be bent or deformed into a different shape

Question 20

Give an example of where shape memory alloys can be used

Answer 20

Dental braces

Question 21

Why are metals good conductors of heat and electricity

Answer 21

Metal structures have delocalised electrons. The delocalised electrons move throughout the giant metallic lattice and can transfer energy quickly

Question 22

What does Must Every Pupil Be Perfect stand for

Answer 22

Methane 
Ethane
Propane
Butane 
Pentane

Question 23

What happens when changing the reaction conditions of a polymer

Answer 23

The properties of the polymer that is produced changes

Question 24

Give an example of a thermosoftening polymer

Answer 24

Poly(ethene)

Question 25

What is a thermosoftening polymer made of

Answer 25

Individual polymer chains that are tangled together

Question 26

What happens to a thermosoftening polymer when heated

Answer 26

It becomes soft and hardens again when it cools.

Question 27

What are the advantages of heating a thermosoftening polymer

Answer 27

It can be moulded into shape and remoulded when heating it again

Question 28

What happens when we heat thermosetting polymers

Answer 28

They do not melt or soften

Question 29

Why do thermosetting polymers set hard when first moulded

Answer 29

Strong covalent bonds form cross-links between their polymer chains. The strong bonds hold the polymer chains in place

Question 30

In thermosoftening polymers are the forces between the polymer chains strong or weak

Answer 30

Weak

Question 31

What happens when the thermosoftening polymer is heated

Answer 31

The weak intermolecular forces are broken and the polymer becomes soft. When the polymer cools down, the intermolecular forces bring the polymer molecules back together so the polymer hardens again

Question 32

What is nanoscience

Answer 32

The study of small particles that are between 1 and 100 nanometres in size

Question 33

What is a nanometre

Answer 33

One billionth of a metre

Question 34

What is a nanoparticle

Answer 34

Something that is a few nanometres in size

Question 35

Give a property of a nanoparticle

Answer 35

Their small sizes give them a very large surface area

Question 36

What does nanotechnology use nanoparticles as

Answer 36

• Highly selective sensors
• Very efficient catalysts
• New coatings
• New cosmetics such as sun screens and deodorants
• Give construction materials special properties

Question 37

What are the risks if nanoparticles are used more and more

Answer 37

There will be a grater oak of them finding their way into the air and into our bodies. This could have unpredictable consequences for our health and the environment. More research needs to be done to find out their effects.