Chemistry exam revision

Question 1

What are the properties of solids?

Answer 1

Very low energy, vibrate, very close to each other.

Question 2

What are the properties of liquids?

Answer 2

Still close to each other, have enough energy to slide over each other.

Question 3

What are the properties of gasses?

Answer 3

Have lots of energy, lots of space between particles, and collide frequently.

Question 4

Explain ionic bonds

Answer 4

Happens between a non-metal and a metal.
Metal loses electrons by transferring it to non-metals. Non-metal gains electrons.

Question 5

What are elements?

Answer 5

Substances that are made of one type of atom.

Question 6

What are molecules?

Answer 6

Two or more atoms joined together.

Question 7

What are compounds?

Answer 7

Two or more elements chemically joined together.

Question 8

What is a mixture?

Answer 8

Two or more substances that are not chemically combined.

Question 9

What is the structure of an Ionic Compound?

Answer 9

Giant Ionic Lattice

Question 10

What are the properties of ionic compounds?

Answer 10

High melting and boiling points. Does not conduct electricity when solid but conducts when in (aq) form.

Question 11

Why does ionic compounds have high melting and boiling points?

Answer 11

Has strong electrostatic forces between ions and therefore needs lots of energy to break the bonds between oppositely charged ions.

Question 12

Why does ionic compounds conduct electricity in solution form but not in solid form?

Answer 12

When in solid form ions are not able to move freely therefore not able to carry any electrical charge.

Question 13

What are the two types of covalent compounds?

Answer 13

Simple molecular and giant covalent

Question 14

What is covalent bonding?

Answer 14

The sharing of electrons between two non-metals.

Question 15

What is the properties of simple molecules?

Answer 15

Low melting and boiling points, does not conduct electricity in any state.

Question 16

Why does simple molecules have a low melting and boiling point?

Answer 16

Have strong covalent bonds but weak intermolecular forces which do not need lots of energy to break.

Question 17

Why do simple molecules do not conduct electricity?

Answer 17

They have no overall charge and no free moving electrons.

Question 18

What are examples of giant covalent?

Answer 18

Diamond, graphite, and silicon dioxide

Question 19

What are polymers?

Answer 19

Polymers are made up of many small molecules to form a long chain.

Question 20

What’s the formula to calculate the relative atomic mass of an atom?

Answer 20

(abundance of isotope 1 x mass of isotope 1) + (abundance of isotope 2 x mass of isotope 2)/ 100

Question 21

What is one use of diamonds?

Answer 21

Embedded in the drills used by oil companies. So that they can drill through layers of rock.

Question 22

What are the properties of the giant covalent structure?

Answer 22

Very high melting and boiling points, insoluble in water, apart from graphite they do not conduct electricity.

Question 23

How many bonds are connected by one atom of carbon in graphite?

Answer 23

Each carbon atom in graphite is covalently bonded to 3 other carbon atoms.

Question 24

How many bonds are connected by one atom of carbon in diamond?

Answer 24

Each carbon atom in diamond is covalently bonded to 4 other carbon atoms.

Question 25

What shape does the carbon atoms form when in graphite?

Answer 25

Hexagons which are arranged in a giant layer.

Question 26

Why is graphite a soft material that feels slippery to touch?

Answer 26

There are no covalent bonds between the layers, only weak intermolecular forces allowing the layers to slide over eachother easily.

Question 27

Why does graphite conduct electricity?

Answer 27

Each carbon atom in graphite is covalently bonded to 3 other carbon atoms. Carbon atoms have 4 electrons in its outer shell for bonding. This leaves one other electron to roam around freely. These are called delocalised electrons.

Question 28

What are fullerenes?

Answer 28

Carbon which from into shapes like cylinders, cages and tubes.

Question 29

What are fullerenes use for?

Answer 29

To transport drugs inside the body, and to reinforce composite materials.

Question 30

What are the characteristics of graphene?

Answer 30

A single layer of graphene is one atom thick and has excellent electrical conductivity.

Question 31

What is the arrangement of a metal?

Answer 31

Metal atoms are arranged in regular layers.

Question 32

Why do metals conduct electricity?

Answer 32

Have a sea of delocalized electrons which can carry electric current.

Question 33

What is metallic bonds?

Answer 33

They contain a sea of free moving electrons which are attracted to the positive metal ions.

Question 34

Why are pure metals malleable and ductile?

Answer 34

The atoms in a pure metal are held together in a giant metallic structure. The regular arrangement allows the atoms to slide over each other quite easily.

Question 35

What are alloys?

Answer 35

A mixture of two or more element, at least one of which is a metal.

Question 36

Why are alloys harder than pure metals?

Answer 36

They have a controlled amount of another atom inside the metal which has a different size compared to the other atoms. This makes it hard for the layers to slide over each other.

Question 37

What allows nanoparticles have different properties compared to bulk materials?

Answer 37

They have a high surface to area to volume ratio, with high percentage of atoms exposed at the surface.

Question 38

What are the use of nanoparticles?

Answer 38

1 Sun creams - nanoparticles are affective at blocking the Sun's rays. 2. Cosmetics - used in face creams, deodorants and shaving products. 3. Medicine - use of nanocages to deliver drugs to sites where they are needed in the body. 4. Catalysts - used in fuel cell materials. 5. Bactericides - nanoparticles can be used to inhibit the growth of bacteria. Used in fridges, sprays used to clean hospitals. 6. Composite materials - incredibly strong yet light nanotubes are being used to reinforce materials.

Question 39

What are the risks of nanoparticles?

Answer 39

Can damage lungs or enter our blood stream if breathed in and if a spark is made by accident near a large quantity of catalyst there could be a violent explosion.