C2a

Question 0

What is an isotope?

Answer 0

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

Question 1

What are compounds?

Answer 1

Compounds are atoms of two or more elements chemically bonded together. It is difficult to separate the elements

Question 3

What is ionic bonding?

Answer 3

Atoms lose or gain electrons to form ions which are strongly attracted to one another

Question 4

Why do atoms react?

Answer 4

To get a full outer shell

Question 5

Describe the structure of a giant ionic lattice

Answer 5

1) Ions closely packed together
2) In a regular arrangement
3) With strong ionic bonds in all directions

Question 6

Why do giant ionic lattices have a high mpt?

Answer 6

Strong electrostatic forces of attraction in all directions. A lot of (heat) energy is needed to break these bonds

Question 7

Why are giant ionic lattices brittle?

Answer 7

When layers are hit, they move and similar charges are next to each other. These repel so the substance breaks apart

Question 8

Do giant ionic lattices conduct electricity?

Answer 8

Only when molten or dissolved as ions are free to move

Question 9

What is covalent bonding?

Answer 9

Bonding between two or more non-metals, in which they share electrons so they both have a full outer shell

Question 10

Which atoms form diatomic molecules?

Answer 10

All group 7, H, N and O

Question 11

Describe the structure of simple molecular substances

Answer 11

1) Strong covalent bonds (intramolecular forces)
2) Weak intermolecular forces
3) No ions

Question 12

Why are simple molecular substances liquids or gases at room temperature?

Answer 12

Weak intermolecular forces so not much (heat) energy is needed to separate them

Question 13

Do simple molecular substances conduct electricity?

Answer 13

No as no ions

Question 14

What is another name for giant covalent structures? Give 3 examples

Answer 14

Macromolecules

Diamond, Silicon dioxide, Graphite

Question 15

Describe the structure of diamond

Answer 15

1) Each carbon atom forms 4 covalent bonds

2) Rigid structure (hardest natural substance)

Question 16

Describe the structure of silica

Answer 16

1) Strong covalent bonds

2) Makes sand

Question 17

Can diamond and silica conduct electricity?

Answer 17

Not even when molten or dissolved as no free ions or electrons

Question 18

Describe the structure of graphite

Answer 18

1) Each carbon atom forms 3 covalent bonds

2) Arranged in layers

Question 19

Why is graphite soft and slippery?

Answer 19

It is made up of layers that can slide over each other

Question 20

Can graphite conduct electricity?

Answer 20

Yes because each carbon atom leaves one delocalised electron

Question 21

Why do giant covalent substances have high mpts?

Answer 21

Strong covalent bonds so a lot of (heat) energy is needed to break the bonds

Question 22

Describe the structure of a metal

Answer 22

1) Positive ions in regular arrangement
2) In a sea of free electrons
3) Opposite forces hold it together

Question 23

Why are metals malleable?

Answer 23

Layers can slide over each other without breaking

Question 24

Do metals conduct electricity?

Answer 24

Yes because delocalised electrons

Question 25

Why are alloys harder than pure metals?

Answer 25

Different sized atoms disrupt the regular arrangement so layers can't slide over each other

Question 26

Give an example of a smart material and what it is used for

Answer 26

Nitol (nickle + titanium) - shape memory | When cool it can bend, when heated it goes to remembered shape - used in glasses and braces

Question 27

What are fullerenes?

Answer 27

Carbon nanoparticles Strong covalent bonds hold it together in balls/ tubes made from hexagonal rings Used to reinforce graphite in tennis rackets

Question 28

Why can nanotubes be used as lubricants?

Answer 28

Tubes can roll over each other as there are no bonds between tubes. Lubricant coatings reduce friction in artificial joints/ gears

Question 29

What can nanoparticles be used for?

Answer 29

``` Catalysts - high SA:volume Highly specific sensors e.g. water purification Cosmetics - no white mark deodorant Deliver drugs in body Tiny electric circuits ```

Question 30

What is the structure of thermosoftening polymers?

Answer 30

Strong covalent bonds to make chains | Weak intermolecular forces - chains free to slide

Question 31

What are the qualities of thermosoftening polymers?

Answer 31

Low mpt Easily remoulded Soft + felxible

Question 32

How are low density polymers made?

Answer 32

E.g. bags + bottles High temp (200) High pressure

Question 33

What is the structure of thermosetting polymers?

Answer 33

Strong covalent bonds | Crosslinks provide stronger intermolecular forces

Question 34

What are the qualities of thermosetting polymers?

Answer 34

High mpt Can't be remoulded Hard + rigid

Question 35

How are high density polymers made?

Answer 35

E.g. drainpipes Low temp + pressure Catalyst

Question 36

What is Ar?

Answer 36

Relative atomic mass - how heavy atoms are compared to C12 (top number)

Question 37

What is Mr?

Answer 37

Relative formula mass - all Ars of a compound added together

Question 38

What is a mole?

Answer 38

The Mr of a substance in grams

Question 39

What is the equation for finding moles?

Answer 39

Moles = mass/Mr

Question 40

How do you find experimental masses?

Answer 40

1) Balance equation 2) Work out moles 3) Ratio using balanced equation 4) Moles * Mr

Question 41

What is the empirical formula?

Answer 41

The experimentally derived ratio of the amount of atoms in a compund

Question 42

How do you find the empirical formula?

Answer 42

1) Write down element and data 2) Divide data by Ar 3) Divide by smallest 4) Make into a whole number

Question 43

What is the equation for % yield?

Answer 43

% yield = actual/ theoretical * 100

Question 44

Why is a high % yield important?

Answer 44

Save resources, money, time, energy

Question 45

Why is % yield never 100%?

Answer 45

1) Products remain on filter paper / glassware 2) Unexpected reactions - useless products 3) Reversible reactions - reaction where the products can themselves react to become the original reactants

Question 46

In reversible reactions, what is the heat transfer?

Answer 46

Exothermic one way means endothermic the other

Question 47

What is paper chromatography?

Answer 47

A method of chemical analysis used to separate substances e.g. dyes

Question 48

How is paper chromatography used?

Answer 48

Pencil (insoluble) baseline on filter paper Shallow solvent in beaker Paper just in solvent

Question 49

What is the Rf value?

Answer 49

Distance travelled by a dye

Question 50

Why are machines often used in chemical analysis?

Answer 50

Faster, more accurate, more sensitive

Question 51

How does gas chromatography work?

Answer 51

Gas carries substance through column | Different masses so different speeds so substance separates

Question 52

What is retention time?

Answer 52

The time of a substance taken to reach the detector

Question 53

How can you tell the number of compounds in a substance?

Answer 53

Number of peaks

Question 54

What does a mass spectrometer do?

Answer 54

Work out the Mr of a compound (molecular ion peak)