Polymers, Giant Covalent Structures and Metallic Bonding

Question 1

What is a Polymer?

Answer 1

Lots of small units linked together to form a long molecule that has repeating sections, all atoms are linked by strong covalent bonds.

Question 2

Why do Polymers take more energy to melt or boil?

Answer 2

They have larger intermolecular forces than simple covalent molecules, therefore require more energy to break them. (Solids at room temp)

Question 3

How are Polymers intermolecular forces compare to Ionic or giant molecular compounds?

Answer 3

The intermolecular forces are still weaker than ionic or covalent, so they generally have lower boiling points than ionic or giant molecular compounds.

Question 4

What is the difference between giant covalent structures and simple molecular substances?

Answer 4

All the atoms are bonded to each other by strong covalent bonds in Giant Covalent Bonds.

Question 5

What are some properties of Giant Covalent Structures?

Answer 5

1) They have very high melting and boiling points, as lots of energy is needed to break bonds.
2) They don’t conduct electricity as they don’t have charged particles, not even Molton (except for some exceptions)

Question 6

What are some example of Giant Covalent Structures?

Answer 6

Diamond and Graphite

Question 7

What are Allotropes?

Answer 7

Different structural forms of the same element.

Question 8

What are the properties of Diamond?

Answer 8

1) Diamond is made up of carbon atoms that each form 4 covalent bonds, makes diamond hard
2) Very high melting point, due to the covalent bonds.
3) Does not conduct electricity because of no free electrons

Question 9

What are the properties of Graphite?

Answer 9

1) Each carbon atom forms 3 covalent bonds, creating sheets arranged in hexagons
2) No covalent bonds between layers, held together weakly, so free to move over each other.
3) High melting point, due to covalent bonds needing lots of energy to break.
4) One electron is delocalised, therefore it can conduct electricity.

Question 10

What are the properties of Graphene?

Answer 10

1) A sheet of carbon atoms joined together in hexagons
2) The sheet is one atom thick, making it two-dimensional compound.
3) Very strong covalent bonds and incredibly light so can be added as a composite material to strengthen without adding too much weight.
4) Contains delocalised electrons and therefore can conduct electricity.

Question 11

What are Fullerenes?

Answer 11

• Molecules of carbon, shaped like closed tubes or
  hollow balls.
• Made up of carbon atoms arranged in hexagons (but
  can also contain pentagons or heptagons)

Question 12

What can Fullerenes be used to do?

Answer 12

‘Cage’ other molecules as it forms around another atom or molecule,

Question 13

What do Fullerenes have that allow them to be good conductors?

Answer 13

Large surface area, so individual catalyst molecules could be attached to fullerenes

Question 14

What else can Fullerenes be used for?

Answer 14

Lubricants

Question 15

What can Fullerenes form?

Answer 15

Nanotubes, tiny carbon cylinders

Question 16

What are some properties of nanotubes?

Answer 16

1) Can conduct both electricity and thermal energy
2) High tensile strength
3) Diameter to length ratio very high
4) Can be used in electronics or to strengthen materials know as “Nanotechnology”

Question 17

What do metals consist of?

Answer 17

Giant structure

Question 18

What does metallic bonding involve?

Answer 18

The outer shell of the metal atoms are delocalised they are strong forces of electrostatic attraction between the positive metal ions and shared negative electrons.

Question 19

What is metallic bonding?

Answer 19

The forces of attraction that hold the atoms together are in a regular structure are known as metallic bonding.

Metallic bonding is very strong

Question 20

Name an example of a substance metallically bonded?

Answer 20

Alloy

Question 21

What state of matter are solids at room temp?

Answer 21

• Most metals are solids at room temperature, due to
  electrostatic forces between metals and the
  delocalised sea of electrons are very strong (which
  needs lots of energy to break)

Question 22

What is the melting and boiling point of metals like?

Answer 22

Very High, due to the strong electrostatic forces

Question 23

Are metals good conductors of heat or electricity?

Answer 23

Yes, as the delocalised electrons carry electrical current and thermal energy through the metal.

Question 24

Are metals Malleable?

Answer 24

Yes, the layers of metals can slide over each other, making them malleable.

Question 25

What is an Alloy?

Answer 25

A mixture of two or more metals or a metal and another element.

Question 26

Why are Alloys harder than normal Metals

Answer 26

The different elements have different sized atoms, so when the elements are mixed with a pure metal it distorts the layers making it more difficult for them to slide over each other