Chemistry Unit 2 Gcse Aqa

Front 1

Name of the number at the bottom of the chemical symbol

Back 1

The atomic number

Front 2

Name of the number at the top of the chemical symbol

Back 2

The mass number

Front 3

How do you find the number of electrons with the atomic number

Back 3

It's the same

Front 4

How is a compound formed

Back 4

When atoms of two or more elements are chemically combined together

Front 5

Definition of an isotope

Back 5

Different atomic forms of the same element which have the same number of protons but a different number of neutrons

Front 6

Give an example of a pair of isotopes

Back 6

Carbon-12 and Carbon-14

Front 7

Which type of bonding is the transferrance of electrons

Back 7

Ionic

Front 8

Why do elements such as sodium, potassium and calcium like to form ionic bonds

Back 8

They have 1 electron in their outer shell

Front 9

Which two groups contain elements which are most likely to form ionic bonds by gaining electrons

Back 9

Groups 6 & 7

Front 10

What kind of structure do ionic compounds have

Back 10

Regular lattice

Front 11

Why do ions 'stay together' in a lattice structure

Back 11

Because of the strong electrostatic forces of attraction between oppositely charged ions in all directions

Front 12

Name an example of a compound in a lattice structure

Back 12

Sodium chloride

Front 13

Name the properties of ionic compounds

Back 13

- High melting points
- High boiling points
- Carry electric current when molten
- Dissolve easily

Front 14

Why do ionic compounds have high melting and

boiling points

Back 14

Because of the strong attraction between the ions. It takes a large amount of energy to overcome this.

Front 15

Which groups are most likely to form ions

Back 15

Groups 1 & 2 and Groups 6 & 7

Front 16

Ions have the structure of what

Back 16

A noble gas

Front 17

Which type of bond is the sharing of electrons

Back 17

Covalent

Front 18

Draw a diagram for the covalent bond of hydrogen

Back 18

Front 19

Draw a diagram for the covalent bond of chlorine

Back 19

Front 20

Draw a diagram for the covalent bond of methane

Back 20

Front 21

Draw a diagram for the covalent bond of hydrogen chloride

Back 21

Front 22

Draw a diagram for the covalent bond of ammonia

Back 22

Front 23

Draw a diagram for the covalent bond of water

Back 23

Front 24

Draw a diagram for the

covalent bond of oxygen

Back 24

Front 25

Name the two types of substances with covalent bonds

Back 25

- Simple molecules
- Giant structures (macromolecules)

Front 26

Why are the melting and boiling points of simple molecular substances low

Back 26

Because of weak intermolecular forces. The molecules are easily parted from each other.

Front 27

What happens when simple molecular substances melt or boil

Back 27

Intermolecular forces are broken

Front 28

What state are most

molecular substances in at room temperature

Back 28

Gases or liquids

Front 29

Why don't molecular

substances conduct

electricity

Back 29

There are no ions so there's no electrical charge

Front 30

What is a synonym for

giant covalent structures

Back 30

Macromolecules

Front 31

What is a lattice

Back 31

A giant ionic structure

Front 32

Why are macromolecules different from lattices

Back 32

Macromolecules have no charged ions

Front 33

How are atoms bonded

together in macromolecules

Back 33

Strong covalent bonds

Front 34

Features of macromolecules?

Back 34

- high melting & boiling points
- don't conduct electricity

Front 35

3 examples of macromolecules?

Back 35

- Diamond
- Silicon dioxide (silica)
- Graphite

Front 36

How many covalent bonds are formed by each carbon atom in diamond

Back 36

4

Front 37

What is diamond used for

Back 37

Drill tips

Front 38

What is sand made of

Back 38

Silicon dioxide

Front 39

In graphite how many

covalent bonds are formed by each carbon atom

Back 39

3

Front 40

What do the three covalent bonds formed by each carbon atom in graphite create

Back 40

Layers which are free to slide over each other

Front 41

What features are created in graphite by the layers formed

Back 41

Makes it soft and slippery

Front 42

How does a pencil work

Back 42

The layers are held together so loosely in graphite that they can be rubbed off on to paper

Front 43

Why can layers be rubbed off on to paper in graphite

Back 43

Because there are weak

intermolecular forces between layers

Front 44

Why is graphite a good conductor of heat and electricity

Back 44

Each carbon atom has one delocalised electron which conducts it

Front 45

What are the properties of metals due to

Back 45

The sea of free/delocalised electrons

Front 46

Where do the delocalised electrons come from

Back 46

The outer shell of every metal atom in the structure

Front 47

Why are metals good conductors of heat and electricity

Back 47

Because the electrons are free to move throughout the structure

Front 48

Why are atoms in metals held together in a regular structure

Back 48

There are strong forces of electrostatic attraction between the positive metal ions and the negative electrons

Front 49

What does the sea of free electrons allow to happen in metals

Back 49

The layers of atoms can slide over each other allowing metals to be bent and shaped

Front 50

Which are harder; pure metals or alloys

Back 50

Alloys

Front 51

What is an alloy

Back 51

A mixture of two or more metals

Front 52

Why are alloys harder than pure metals

Back 52

Different elements have different sized atoms. The new metal atoms will distort the layers of metal atoms making it more difficult for them to slide over each other.

Front 53

Name the 4 types of structures

Back 53

- Giant ionic
- Simple molecular
- Giant covalent
- Giant metallic

Front 54

What do smart materials do

Back 54

Behave differently depending on the

conditions

Front 55

Give an example of a smart material

Back 55

Nitinol, a shape memory alloy

Front 56

State the properties of nitinol

Back 56

- When cool it's bendable and you are able to twist it like rubber
- When heated above a certain temperature it goes back to a remembered shape

Front 57

Give two examples of uses for nitinol

Back 57

- Glasses frames, if accidentally bent they can be put in a bowl of hot water and they'll jump back into shape.
- Dental braces, it warms in the mouth and tries to return to a remembered shape and pulls the teeth with it.

Front 58

What are nanoparticles

Back 58

Tiny particles, 1-100 nanometres across

Front 59

How many atoms do nanoparticles contain

Back 59

Roughly a few hundred

Front 60

Nanoparticles include what

Back 60

Fullerenes

Front 61

What are fullerenes

Back 61

Molecules of carbon, shaped like hollow balls or closed tubes.
The carbon atoms are arranged in hexagonal rings.

Front 62

What is a nanotube

Back 62

Fullerenes joined together.
They're tiny hallow carbon tubes, a few nanometres across.

Front 63

Which type of bond in nanotubes make them strong

Back 63

Covalent

Front 64

Give an example of an object in which nanotubes are used

Back 64

Used to reinforce graphite in tennis rackets

Front 65

Using nanoparticles is known as

Back 65

Nanoscience

Front 66

List possible uses for nanoparticles

Back 66

- Catalysts due to large surface area to volume ratio
- Highly specific sensors to test water purity
- To make stronger, lighter building materials
- Cosmetics (sun cream, deodorant)
- Electric circuits
- Artificial joints
- Gears

Front 67

Explain the idea behind nanomedicine

Back 67

Tiny fullerenes can be absorbed more easily by the body than most particles. Drugs can then be delivered right into the cells where they're needed.

Front 68

Why can nanotubes be used in electric circuits

Back 68

They conduct electricity

Front 69

Why can fullerenes be used to aid artificial joints and gears

Back 69

Lubricant coatings are being developed using fullerenes. They reduce friction a bit like ball bearings so can be used in artificial joints etc.

Front 70

What determines the properties of plastics

Back 70

Forces between molecules

Front 71

What holds the atoms together in long chains in plastics

Back 71

Strong covalent bonds

Front 72

Describe polymers with weak forces

Back 72

Individual tangled chains, held together by weak intermolecular forces which are free to slide over each other.

Front 73

Describe polymers with strong forces

Back 73

Strong intermolecular forces between polymer chains called crosslinks, that hold the chains together.

Front 74

Why can thermosoftening plastics be melted

Back 74

They don't have cross-linking between chains. The forces between them are really easy to overcome.

Front 75

Why can't thermosetting plastics be melted

Back 75

They have crosslinks which hold the chains together in a solid structure.

Front 76

Give examples of two types of polythene made using different conditions

Back 76

- Low density polythene
- High density polythene

Front 77

How is LDPE made & what are its properties

Back 77

By heating ethene to about 200 degrees C under high pressure.
Flexible, used for bags and bottles.

Front 78

How is HDPE made & what are its properties

Back 78

Made at a lower temperature than LDPE and pressure (with a catalyst).
More rigid than LDPE, used for water tanks and drainpipes.