Topic 2-Bonding, Structure And Properties Of Matter

Question 1

What is an ion?

Answer 1

Charged particles.

Question 2

Why are ions formed?

Answer 2

Aroms lose or gain electrons to get a full outer shell so they can become stable.

Question 3

What happens to metals when they form ions?

Answer 3

They lose electrons from their outer shell to form positive ions.

Question 4

What happens to non metal when they become ions?

Answer 4

They gain electrons to their outer shell to form negative ions.

Question 5

What happens during ionic bonding between a metal and a non metal?

Answer 5

The metal atom loses electrons to form a positively charged ion and non metals gain electrons to form negatively charged ions.
The opposite ions are strongly attracted by electrostatic forces. This is an ionic bond.

Question 6

How is the ionic compound sodium chloride formed?

Answer 6

It is in a structure called a giant ionic lattice.
The are closely packed together in a regular lattice and they have very strong electrostatic forces of attraction between the oppositely charged ions in all directions.

Question 7

What are the properties of ionic compounds?

Answer 7

They have high melting points and high boiling points due to the strong bonds between the ions so it takes alot of energy to overcome the attraction.
When they are solid they cannot conduct electricity.
When they are melted they are free to move so they carry electric current.
They dissolve easily in water so the ions are separate and are free to move in the solution so theyll carry electric current.

Question 8

What happens during covalent bonding?

Answer 8

The positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces making covalent bonds very strong.
They only share electrons in their outer shells to give a full outer shell which makes them stable.
It happens in the compounds of non metals and in non metal elements.

Question 9

What are the properties of simple molecular substances (covalent bonding)?

Answer 9

The molecules are held together by very strong covalent bonds but weak forces of attraction.
They melting and boiling points are low as the molecules can be easily parted as you only have to break the intermolecular forces.
Most molecular substances are gases or liquids at room temperature.
As the molecules get bigger the strength of the intermolecular forces increase so more energy is needed to break them and the melting and boiling points increase.
They dont conduct electricity as they arent charged as there are no free electrons or ions.

Question 10

What is a polymer?

Answer 10

A long chain of repeatinf units.

Question 11

How are polymers joined together?

Answer 11

Covalent bonds.

Question 12

What are the intermolecular forces like in polymer molecules?

Answer 12

They are larger than simple covalent molecules so more energy is needed to break them so they are solid at room temperature.
The intermolecular forces sre still weaker than ionic or covalent bonds so they generally have lower boiling points than ionic or giant molecular compounds.

Question 13

What are the structures of giant covalent structures like?

Answer 13

All the aroms are bonded together by strong covalent bonds.
They have high melting and boiling points as alot of energy is needed to break the covalent bonds.
They dont conduct electricity as they dont contain charged particles - not even when molton (except graphite).

Question 14

What are the covalent bonds in diamond?

Answer 14

Each carbon atom has four covalent bonds in a rigid giant covalent structure.

Question 15

What are the covalent bonds in graphite?

Answer 15

Each carbon atom forms three covalent bonds to create layers of hexagons.
Each carbon atom has one delocalised electron.

Question 16

What is the structure of diamond?

Answer 16

It is a giant covalent structure with carbon atoms that form 4 covalent bonds, making diamond really hard.
The strong covalent bonds take alot of energy to break diamond giving it a very high melting point.
It doesnt conduct electricity as it has no free electrons or ions.

Question 17

What is an allotrope?

Answer 17

A different structual form of the same element in the same physical state.

Question 18

What is the structure of graphite?

Answer 18

Each carbon atom only forms three covalent bonds. This created sheets of carbon arranged in hexagons.
There arent any covalent bonds between the layers and are held together weakly so they are free to move over each other. This making graphite soft and slippery, like a lubricating material.
It has a high melting pint as alot of energy is needed to break the covalent bonds.
Carbon has one delocalised electron so it can conduct electricity and thermal energy.

Question 19

What is the structure of grahpene?

Answer 19

It is a sheet of carbon atoms joined together in hexagons.
It is one atom thick making it a 2D compound.
Network of covalent bonds makes it strong.
It is light so can be added to composite materials to improve strength without adding much weight.
It has delocalised electrons so it can conduct electricity through the whole structure.

Question 20

What are fullerenes?

Answer 20

They are molecules of carbon shaped like closed tubes or hollow balls.

Question 21

What are fullerenes made up of?

Answer 21

Carbon atoms arranged in hexagons but can also contain pentagons or heptagons.

Question 22

What are fullerenes used for?

Answer 22

They can cage other molecules. They can form around another atom which traps it inside. This can be used to deliver a drug into the body.
They have a huge surface area making them good industrial catalysts.
They can also be good lubricants.

Question 23

What are the structure of nanotubes?

Answer 23

They are tiny carbon cylinders.
Theyl ratio between the length and diameter is very high.
It can conduct both electricity and thermal energy.
They have a high tensile strength (dont break when stretched).
Nanotubes can be used to strenthen materials without adding much weight.

Question 24

What are the structure of metals?

Answer 24

They are a giant structure.
The electrons in the outer shells of the metal atoms are delocalised. There are strong forces of attraction between the positive metal ions and the negative electrons.

Question 25

What is metallic bonding?

Answer 25

The forces of attraction hold the atoms together in a regular structure. Metallic bonding is very strong.

Question 26

What are the properties of metals?

Answer 26

They are solid at room temperature. This is because the electrostatic forces between the metal atoms and the delocalised electrons are very strong and need alot of energy to be broken so the metals have very strong boiling and melting points.
The delocalised electrons carry electrical current so they are good conductors of electricity and heat.
They are malleable as the layers of metal can slide over each other.

Question 27

What is an alloy?

Answer 27

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

Question 28

Why are alloys more useful than pure metals?

Answer 28

Pure metals are often to soft so alloys are made as they are harder and more useful than pure metals.
This is because different elements have different sized atoms so the new metal will disort the layers of metal atoms making it more difficult for them to slide over each other.

Question 29

What is the structure of a solid?

Answer 29

There are strong forces of attraction which holds them close together in fixed positions to form a lattice arrangement.
They dont move from their positions so all solids keep a definite shape and volume.
The particles vibrate so the hotter the solid the more it vibrates.

Question 30

What is the structure of a liquid?

Answer 30

There are weak forces of attraction between the particles.
They are randomly arranged and free to move past each other but they stick closely together.
They have a volume but not a definite shape.
The particles are constantly moving with random motion. The hotter the liquid the faster they move.

Question 31

What is the structure of gases?

Answer 31

The forces of attraction between the particles is very weak. They are free to move and are far apart.
They dont have a definite shape or volume and will always fill a container.
They move constantly in a random motion. The hotter the gas gets the faster they move. The gases will either expand when heated or their pressure increases.

Question 32

Describe how substances change from one state to another.

Answer 32

When a solid is heated its particles gain more energy.
This makes the particles vibrate more weakening the forces that holds the solid together.
At the melting point the particles have enough energy to break free. This is melting and a solid turns into a liquid.
When a liquid is heated the particles get even more energy.
The energy makes the particles move faster which weaken and breaks the bonds holding the liquid together.
At the boiling point they have enough energy to break their bonds. Boiling or evaporating is when a liquid becomes a gas.
As a gas cools it no longer has enough energy to overcome the forces of attraction between them.
Bonds form between the particles.
At the boiling point many bonds have formed between the gas particles and the gas becomes a liquid. This is condensing.
When a liquid cools the particles have less energy so move around less.
There is not enough energy to overcome the attraction so more bonds form between them.
At the melting point so many bonds have formed between the particles that theyre held in place. The liquid becomes a solid this is freezing.

Question 33

What does aqueous mean?

Answer 33

Dissolved in water.