2a

Question 1

What is the mass number?

Answer 1

The total number of protons and neutron

Question 2

What is the atomic number?

Answer 2

The number of protons

Question 3

What are the masses of protons, neutrons and electrons?

Answer 3

Protons= 1
Neutrons= 1
Electron = very small

Question 4

What is a compound?

Answer 4

Atoms of two or more elements chemically combined together

Question 5

Define isotope

Answer 5

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

Question 6

What happens in ionic bonding?

Answer 6

Atoms lose or gain electrons to form charged particles (ions) which are then strongly attracted to one another

Question 7

What kind of structure do Ionic compounds always have?

Answer 7

Regular lattice

Question 8

What do ionic compounds always have in them?

Answer 8

Giant ionic lattices

Question 9

In ionic compounds how strong are the electrostatic forces of electron between the oppositely charged ions, in all directions

Answer 9

Very strong

Question 10

Give an example of a giant ionic lattice

Answer 10

Salt (sodium chloride)

Question 11

Name 3 properties of ionic compounds

Answer 11

High melting points, high boiling points due to strong attraction between the ions & dissolve easily in water

Question 12

What is covalent bonding?

Answer 12

When atoms share electrons to complete their outer shell

Question 13

What are the two kinds of covalent substances?

Answer 13

Simple molecular substances, giant covalent structures (macromolecules)

Question 14

Describe the properties of simple molecular substances

Answer 14

Atoms form very strong covalent bonds to form small molecules of several atoms. Forces of attraction between molecules is weak. low bp &mp. don’t conduct electricity

Question 15

Describe the properties of giant covalent structures

Answer 15

No charged ions, atoms bonded to each other by strong covalent bonds. high bp & mp. Don’t conduct electricity

Question 16

Give three examples of simple molecular substances

Answer 16

Chlorine, Oxygen, Water

Question 17

Give three examples of giant covalent structures

Answer 17

Diamond, Graphite, Silicon Dioxide (Silica)

Question 18

What is the hardest natural substance?

Answer 18

Diamond

Question 19

What is each grain of sand made up of?

Answer 19

One giant structure of silicon and oxygen

Question 20

Which non-metal can conduct heat and electricity well and why?

Answer 20

Graphite- three covalent bonds, layers free to slide over each other, weak intermolecular forces between layers. Each carbon atom has one delocalised electron, conduct heat and electricity

Question 21

What are metal properties due to?

Answer 21

The sea of free electrons

Question 22

Name 3 properties of metals due to their electrons

Answer 22

Good conductors of heat and electricity because free to move, hold the atoms together in a regular structure due to strong electrostatic attraction between positive metal ions and negative electrons. Allow layers of atoms to slide over each other, allowing metals to be bent and shaped.

Question 23

What are harder alloys or pure metals and why?

Answer 23

Alloys, have different sized atoms so more difficult for them to slide over each other

Question 24

Give an example of a smart material

Answer 24

Nitinol

Question 25

Roughly how many atoms do nanoparticles contain?

Answer 25

A few hundred atoms

Question 26

What are fullerenes?

Answer 26

Molecules of carbon, shaped like hollow balls or closed tubes. Different fullerenes contain different numbers of carbon atoms.

Question 27

Fullerenes can be joined together to form…

Answer 27

Nanotubes

Question 28

Name 3 useful aspects of nano science

Answer 28

Huge surface area to volume ratio for catalysts, stronger and lighter building materials, conduct electricity so could be used for computer chips

Question 29

What determines the properties of plastics?

Answer 29

Forces between molecules

Question 30

If there are weak intermolecular forces in a polymer what can it do and what type of polymer is it?

Answer 30

Free to slide over each other and creates thermo-softening polymers

Question 31

Describe thermo-softening polymers

Answer 31

Don’t have cross-linking between chains, forces between chains are easy to overcome, easy to melt the plastic.

Question 32

If there are strong intermolecular forces in a polymer what does it have and what type of polymer is it?

Answer 32

Crosslinks that hold the chains firmly together and creates thermosetting polymers

Question 33

Describe thermosetting polymers

Answer 33

Have cross-links between chains, solid structure, doesn’t soften when heated, strong, hard rigid

Question 34

What two things will affect the properties of a polymer?

Answer 34

Starting materials and reaction conditions

Question 35

What hold the atoms together in long chains in polymers?

Answer 35

Strong covalent bonds

Question 36

How is Low density (LD) polythene made and what is it used for?

Answer 36

Made by heating ethene to about 200c under high pressure. Its flexible and is used for bags and bottles

Question 37

How is High density (HD) polythene made and what is it used for?

Answer 37

Made at lower temperature and pressure (with a catalyst). It is more rigid and is used for water tanks and drainpipes

Question 38

What is relative atomic mass?

Answer 38

Mass number

Question 39

What is the relative formula mass?

Answer 39

All relative atomic masses added together

Question 40

What is one mole of a substance equal to?

Answer 40

The relative formula mass in grams

Question 41

What is the equation for working out the number of moles in a substance?

Answer 41

Number of moles = Mass in g (of element or compound / Relative formula mass

Question 42

What is the equation to calculate the percentage mass of an element in a compound?

Answer 42

Relative atomic mass x No. of atoms (of that element) / RFM (of whole compound) x100

Question 43

How do you work out the empirical formula?

Answer 43

list all the elements in the compound with their experimental masses or percentages, divide each mass by the relative atomic mass for that element, make numbers nicer by multiplying and/or dividing, ratio in simplest form is the empirical formula.

Question 44

How do you calculate masses in reactions?

Answer 44

Write out the balanced equation, work out the RFM for the bits you need, apply rule divide to get one, then multiply to get all

Question 45

What is the formula to calculate the percentage yield?

Answer 45

Percentage yield= actual yield (grams) / predicted yield (grams) x100

Question 46

Give three possible explanations for why there is never an 100% yield

Answer 46

The reaction could be reversible, when filtering nearly always lose a bit of the solid or liquid when its separated from the reaction mixture, can be other unexpected reactions which use up the reactants

Question 47

How can artificial colours be separated?

Answer 47

Paper chromatography

Question 48

How does paper chromatography work?

Answer 48

Put spots of coloured solution on a pencil baseline on filter paper, roll up sheet and put it in beaker with solvent. Solvent seeps up paper taking dyes with it.

Question 49

Name three advantages to using instrumental methods to identify elements and compounds

Answer 49

Very sensitive (can detect even the tiniest amounts of substances), very fast ad tests can be automated, very accurate

Question 50

What can be used to identify substances?

Answer 50

Gas chromatography

Question 51

Explain the process of gas chromatography

Answer 51

A gas is used to carry substance through a column packed with solid material. The substances travel through the tube at different speeds so their separated. The time they take to reach the detector is the retention time, used to identify the substances. Record draws a gas chromatograph.

Question 52

On a gas chromatograph, what does the number of peaks and the position of the peaks show?

Answer 52

The no. of peaks shows the no. of different compounds in the sample, position of peaks shows the retention time for each substance

Question 53

What is retention time?

Answer 53

Time taken for a compound to reach the detector in gas chromatography

Question 54

What can a gas chromatography column be linked up to and what can it do?

Answer 54

Can be linked to a mass spectrometer, can identify the substances more accurately.