C2 Bonding, Isotpes And Polymers

Question 0

Explain what is meant by the term isotope.

Answer 0

Isotopes are different atomic forms of the same element, which have the same number of protons but a different number of neutrons.

Question 1

What is a compound?

Answer 1

It is a substance formed when two or more different types of atoms bond together.

Question 2

What is the top number on a atomic symbol?

Answer 2

Mass number.

Question 3

What is the bottom number on a atomic symbol?

Answer 3

Atomic number.

Question 4

Give an example of an isotope.

Answer 4

Carbon 12 and carbon 14. The latter has an extra two neutrons.

Question 5

What so all isotopes of a partially atom have the same.

Answer 5

The same atomic number but they can have different mass numbers.

Question 6

What is ionic bonding?

Answer 6

When atoms lose or gain electrons to form charged ions.

Question 7

Explain the structure of ionic compounds.

Answer 7

They always have a giant ionic lattice which is a closely packed lattice arrangement.
They have a very strong electrostatic force between all the oppositely charged particles.

Question 8

What are the properties of ionic compounds?

Answer 8

High melting and boiling points because of the strong forces of attraction. It takes a lot of energy to overcome this but when they are melted, they will have free ions meaning they will conduct electricity.
They dissolve easily in water. The ions separate and are free to move so it will conduct electricity.

Question 9

Which elements are most likely to form ionic bonds.

Answer 9

Those in groups 1,2,6 and 7

Question 10

How does one draw the electronic configuration of an ion.

Answer 10

Draw out the atom with the right number of electrons, put it in a square bracket and write the charge on the outside of it.

Question 11

Which compounds form covalent bonds?

Answer 11

H”2” Cl”2” CH”4” HCl NH”3” H”2”O O”2”

Question 12

Explain the structure of simple molecular substances.

Answer 12

Strong covent bonds form to bring the atoms together forming molecules. However the forces between these molecules is very weak.

Question 13

What are the properties of simple molecular substances?

Answer 13

Low melting and boiling points because the molecules are easily parted.
Normally gases or liquids at room temperature. Can be solids.
A lack of ions means they don’t conduct electricity.

Question 14

Explain the structure of giant covalent structures and the properties.

Answer 14

Similar to giant ionic structure but there are no charged particles.
The atoms bond with strong covalent bonds.
High melting and boiling points.
Don’t ever conduct electricity (except graphite)

Question 15

What are the three main examples of giant covalent structures?

Answer 15

Diamond, silicon dioxide(silica) and graphite.

Question 16

Describe diamonds.

Answer 16

Each carbon atoms forms four covalent bonds with four other carbons. Very strong so it is used in drill tips. Also pretty and sparkly.
High thermal conductivity because of the strong covalent bonds.
Can be made by putting carbon under immense pressure and heat.

Question 17

Describe silica.

Answer 17

It’s silicon dioxide. It is what sand is made of.
Very hard with a high melting point.
Insoluble in water.
Doesn’t conduct electricity.

Question 18

Describe graphite.

Answer 18

Each atom only forms three other covalent bonds. This creates layers which can slide over each other. There are weak inter molecular forces. This makes graphite soft so it can be used in pencils and as a lubricant.
It is also the only non-metal that is a good conductor of electricity and heat. This is because each atom has a delocalised electron as carbon has four electrons on the outer shell but only three bonds are made.
High melting point.

Question 19

Explain the properties and structure of giant metallic structures.

Answer 19

The metallic bonds create de-localised electrons which come from the outer shell of the atoms.
These electrons mean it conducts heat and electricity.
They hold the structure together as there are strong forces of attraction between the positive metal ions and the negative electrons.
There are in a regular structure in layers.
This also means the layers of atoms can slide over each other so it can be bent and shaped.

Question 20

What are smart materials?

Answer 20

They behave differently depending on the conditions e.g. Temperature.
Nitinol is one. It is an alloy of nickel and titanium. When cool it can be bent and twisted but if you heat it up, it returns to its original shape.
It can be used in glass frames. If they are bentley can be put in a bowl of hot water to fix them.
They can also be used in braces. They will pull teeth together in the warm mouth.

Question 21

How big is a nano particle ?

Answer 21

1nm = 0.000000001 m

Question 22

What are nano particles?

Answer 22

Very small things between 1-100 nm across. They usually contain only a few hundred atoms.
Theses include fullerenes. These are molecules of carbon shaped like hollow ball or closed tubes. The atoms are arranged in hexagonal rings.

Question 23

What are nanotubes ?

Answer 23

They can are tubes of carbon atoms they are very strong because of the very strong covalent bonds. They can be used in tennis rackets.

Question 24

What are the possible new uses of nano particles?

Answer 24

They have a large surface area to volume ratio so would be good catalysts.
They can make highly specific sensors which are al ready being used to test water purity.
They can be used to make stronger, light building materials.
Cosmetics like sun tan cream and deodorant use them so they work but don’t leave white marks.
They could be used in medicine. They are absorbed more easily into the body meaning they would be good at delivering drugs.
They conduct electricity so could be used in electrical circuits.
They could be used as lubricants.

Question 25

Which type of bonds are found in plastics?

Answer 25

Covalent bonds. They hold the atoms in long chains.

Question 26

Explain the structure and properties of thermosoftening plastics.

Answer 26

Chains of polymers are tangled together. They can slide over each other.
They are easy to melt and can be remoulded easily.

Question 27

Explain the structure and properties of thermosetting plastics.

Answer 27

The chains of polymers have strong inter molecular forces between them. These act as cross links as they hold them together.
These plastics are harder and rigid and don’t soften when heated.

Question 28

How is low density polythene made?

Answer 28

Ethane is heated to 200C with 2000 atmospheres of pressure.

This make it flexible and it is used for bags and bottles.

Question 29

How is high density polythene made ?

Answer 29

60C with a few atmospheres of pressure and a catalyst. It is more rigid and is used in water tanks and drain pipes.

Question 30

What might giant covalent structures also be known as?

Answer 30

Macromolecules.

Question 31

What is metallic bonding ?

Answer 31

The strong electrostatic forces of attractions between positive ions and negative electrons.