Structure and Properties of Matter.

Question 1

What are ionic compounds called ?

Answer 1

Giant ionic lattice.

Question 2

How are ions held together in giant ionic lattices ?

Answer 2

By strong electrostatic forces of attraction between oppositely charged ions in all directions.

Question 3

What are the properties of giant ionic lattices ?

Answer 3

They have high melting and boiling points, due to strong bonds between ions.
Can conduct electricity when molten or dissolved, as ions are free to move and carry an electrical charge.
They are brittle as if pressure is applied the alignment of positive and negative ions shifts.

Question 4

How are ions held together in simple molecular substances ?

Answer 4

Ions share electrons to form strong covalent bonds, these molecules are then held together by weak intermolecular forces.

Question 5

What are the properties of simple molecular substances ?

Answer 5

Very low melting and boiling points as you only need to overcome the very weak intermolecular forces.
As the molecules get bigger the strength of the intermolecular forces increases.
Don’t conduct electricity as they aren’t charged.

Question 6

What are polymers ?

Answer 6

Polymers are long molecules made of lots of small repeating units all joined by strong covalent bonds.

Question 7

What are the properties of polymers ?

Answer 7

The intermolecular forces between polymer molecules are larger than in simple covalent molecules and therefore have a higher melting and boiling point.
However they have lower boiling points than ionic or giant molecular compounds.
Insulators of both heat and electricity.

Question 8

How are ions held together in giant covalent structures ?

Answer 8

All atoms are covalently bonded to each other.

Question 9

What are the properties of giant covalent structures ?

Answer 9

High melting and boiling points as lots of energy is required to break the covalent bonds.
They don’t conduct electricity ( except from graphite).

Question 10

What is the structure of diamond ?

Answer 10

Diamond is a giant covalent structure, it is made of carbon atoms that covalently bond with 4 other carbon atoms.

Question 11

What are the properties of diamond ?

Answer 11

Very hard and high MP and BP as it has 4 strong covalent bonds per atom which require a lot of energy to break.
Don’t conduct electricity as it has no free electrons or ions.

Question 12

What are allotropes ?

Answer 12

Different structural forms of the same element in the same physical state.

Question 13

What is the structure of graphite ?

Answer 13

Each carbon atom has 3 covalent bond with other carbon atoms creating sheets of carbon atoms arranged in hexagons.
There aren’t any covalent bonds between the layers.

Question 14

What are the properties of graphite ?

Answer 14

Graphite is soft and slippery as the layers are only held together by weak intermolecular forces so they slide over each othe easily, this makes it a good lubricant.
It has a high melting point, as the covalent bonds require lots of energy to break.
Graphite conducts electricity and thermal energy as only 3 out of 4 of carbon’s outer electrons are used in bonds so each carbon atom has 1 electron that is delocalised and is free to move around to structure.

Question 15

What is graphene ?

Answer 15

Graphene is a sheet of carbon atoms joined together in hexagons, it is just one atom thick, (two dimensional).
One layer of graphite.

Question 16

What are the properties of graphene ?

Answer 16

Strong due to the covalent bonds.
Very light so it can be added to other materials to improve their strength without adding much weight.
Can conduct electricity like graphite.

Question 17

What is a fullerene ?

Answer 17

Molecules made of carbon, shaped like closed tubes or hollow spheres.

Question 18

What was the first fullerene to be discovered and molecular formula ?

Answer 18

Buckminsterfullerene, C⁶⁰.

Question 19

What can fullerenes be used for and why ?

Answer 19

Drug delivery - hollow tubes make it easy to place drugs inside the fullerene and place inside the body. So the drugs are not rejected.
Industrial catalysts - large surface area means that catalyst molecules. An be attached to the fullerenes.
Lubricant.

Question 20

What can nanotubes be used for and why ?

Answer 20

Strengthening materials (tennis rackets) - have a high tensile strength and don’t add much weight.
Electronics - conducts bother electricity and thermal energy.

Question 21

How are ions held together in metallic bonding ?

Answer 21

There are strong electrostatic forces of attraction between the positive metal ions and the shared negative electrons from the outer shells, which are delocalised.

Question 22

Properties of metallic bonding ?

Answer 22

High melting and boiling points, due to strong electrostatic forces of attraction.
Good conductors of heat and electricity, due to the delocalised electrons which are free to move around the structure and carry a charge.
Malleable, as the layers of atoms in metals can slide over each other.

Question 23

Why are alloys stronger than pure metals ?

Answer 23

Different sized atoms means that it is difficult to slide over each other making them stronger ?

Question 24

What size are nanoparticles ?

Answer 24

They have a diameter between 1nm and 100nm (100 X 10-⁹).

Question 25

As you decrease the size what happens to the sa to volume ratio ?

Answer 25

It increases.

Question 26

What does a high sa to volume ratio mean for the material?

Answer 26

You will need less of a material as nanoparticles than in bulk when using as a catalyst.
Properties can be different in bulk.

Question 27

Uses of nano particles ?

Answer 27

In cosmetics, e.g. sunscreen as it gets into the pores to protect the skin better.
In electric circuits as they can conduct electricity.
In surgical masks and dressings as they have antibacterial properties.

Question 28

Disadvantages of nanoparticles ?

Answer 28

Their affect on the body isn’t fully understood, we don’t know the long term effects it could have on our cells.
It may also be harmful to the environment.