C2a

Question 1

Proton

Answer 1

Charge: +1, Mass: 1

Question 2

Neutron

Answer 2

Charge: 0, Mass: 1

Question 3

Electron

Answer 3

Charge: -1, Mass: 0

Question 4

Mass number

Answer 4

Number of protons + number of neutrons in the nucleus of an atom. (top number)

Question 5

Atomic/proton number

Answer 5

Number of protons/ (=) number of electrons in the nucleus of an atom. (bottom number)

Question 6

Isotope

Answer 6

An atom of the same element but with a different number of neutrons, so it has a different mass number.

Question 7

Element

Answer 7

A substance containing only one type of atom.

Question 8

Compound

Answer 8

Two, or more atoms that are chemically bonded together.

Question 9

Mixture

Answer 9

Two, or more atoms (or compounds) that are not chemically bonded together.

Question 10

Ion

Answer 10

An atom that gains, or loses electrons to gain a charge. By losing electrons they become positive (cation), and by gaining electrons they become negative (anion).

Question 11

Complex

Answer 11

A species that contains more than one atom e.g. NH4

Question 12

Ionic bonding

Answer 12

M + NM. Metal loses electrons to become positive. Non-metal gains electrons to become negative. e.g. NaCl, CaCl2, MgO

Question 13

Ionic compound

Answer 13

M + NM. Consist of giant ionic lattices, held together in a regular arrangement by strong, electrostatic forces of attraction between the oppositely charged positive metal ions, and the negative non-metal ions. High mpt/bpt, conduct electricity when melted or dissolved.

Question 14

Covalent bonding

Answer 14

NM + NM. Non-metals share electrons to get a FOS. e.g. HCl, Methane: CH4, CO2, CO.

Question 15

Covalent bond

Answer 15

A shared pair of electrons.

Question 16

Covalent substance: Simple molecular

Answer 16

Very strong covalent bonds between molecules. Weak intermolecular forces. Low mpt/bpt; gases, or liquids at room temperature, and don’t conduct electricity as they have no ions, or free electrons.

Question 17

Covalent substance: Giant covalent/macromolecules

Answer 17

Every atom is bonded to multiple atoms by very strong covalent bonds. Very high mpt/bpt, solid at room temperature, don’t conduct electricity (except graphite) even when molten as no free ions/electrons. e.g. diamond, silicon dioxide (silica), graphite.

Question 18

Diamond (Giant covalent/macromolecule)

Answer 18

Each carbon has 4 bonds. hardest natural substance, very high mpt/bpt, doesn’t conduct electricity at all.

Question 19

Silicon dioxide/silica (Giant covalent/macromolecule)

Answer 19

Sand (each grain is one giant structure of silicon, and oxygen). Each carbon has 4 bonds. very high mpt/bpt, doesn’t conduct electricity at all.

Question 20

Graphite (Giant covalent/macromolecule)

Answer 20

Carbon atoms only form 3 covalent bonds, this makes free sliding layers so it is soft, and slippery because of the weak intermolecular forces. It is the only non-metal that is a good conductor of heat, and electricity as it has free electrons (because of carbon bonding 3, not 4 times).

Question 21

Metallic structure

Answer 21

M + M. Metals are a giant structure that consist of a regualr arrangement of positive metal ions in a ‘sea’ of free/delocalised negative electrons. They are held together by the strong electrostatic forces of attraction between the positive ions, and negative electrons. They are also positioned in layers. This means that they are malleable/ductile as the layers can slide over each other.

Question 22

Alloy

Answer 22

A material that is composed of at least two metals (or a metal, and a non-metal). Alloys (like steel) are harder than normal metals as the layers of ions are locked in place, and cannot slide over each other. This is because alloys are made of different sized atoms.

Question 23

Smart Materials

Answer 23

The properties of the material change depending on the conditions, e.g. temperature. An example of a smart material is Nitinol (a “shape memory alloy”). Nitinol’s shape changes when heated, and returns to its original shape at a certain temperature. This can be used in dental braces, or in frames for glasses.

Question 24

Nanoscience

Answer 24

The study of very small things (x10 to the power of -9).

Question 25

Nano materials

Answer 25

x10 to the power of -9. For example, Bucky Balls, and fullerenes have a huge surface area to volume ratio so they could make a new industrial catalyst. They are stronger, and lighter so they could be useful as building materials. Some other uses include in medicine, and in computer chips.

Question 26

Polymer

Answer 26

Plastics

Question 27

Thermo-softening polymer

Answer 27

Weak forces of attraction between polymer molecules. Low mpt/bpt, easily remoulded, soft + flexible, e.g. plastic bags.

Question 28

Thermo-setting polymer

Answer 28

Polymers are held together firmly by crosslinks. High mpt/bpt. Cannot be remoulded easily, hard + rigid, e.g. rulers, yogurt pots.

Question 29

Low density polyethene

Answer 29

Ethene (+ 200 degrees celcius + high pressure) -> flexible, light polyethene (e.g. plastic bags)

Question 30

High density polyethene

Answer 30

Ethene (+ low temp/60 degrees celcius + low pressure + catalyst) -> hard, rigid polyethene (e.g. drainpipes)

Question 31

Relative atomic mass

Answer 31

Ar. A measure of how heavy an atom of an element is relative to a C12 atom. (top number) e.g. Mg:24

Question 32

Relative formula mass

Answer 32

Mr. A measure of the individual elements in the formula of a molecule. (Ar s added together) e.h. H2O: 1+1+16=18

Question 33

Percentage yield

Answer 33

% yield = actual yield/theoretical yield x 100
We don’t always get 100% yield as some of the useful product may have been left on the filter paper/glassware; it may be a reversible reaction; or you may get other, non-useful products.
High yield is important in industry as it saves money/increases profit, and saves resources.

Question 34

Reversible reaction

Answer 34

A reaction where the products can react, and convert back into the reactants. e.g. ammonium chloride >< ammonia + hydrogen chloride.

Question 35

Percentage mass

Answer 35

% mass= (Ar x No atoms)/Mr x 100 “no more mister nice guy”

Question 36

Empirical formula

Answer 36

The experimentally derived ratio of the amount of atoms in a compound. Method:

1) Write the symbols.
2) Use the data in the question (mass/percentage)
3) Divide by the Ar of it.
4) Divide by the smallest (to get a 1:x ratio)
5) Convert to a whole number ratio.
6) Put the ratio into the formula WxYz

Question 37

Mole

Answer 37

One mole of a substance is the Ar, or Mr of it expressed in grams. n=m/Mr “no more mister nice guy”

Question 38

Calculating reacting masses

Answer 38

Method:

1) Balance the equation.
2) Calculate the No moles of what you can (data given)
3) Get the No moles of the unknown (using balanced equation ratio)
4) Calculate the mass of the unknown using n=m/Mr

Question 39

Paper chromotography

Answer 39

(See diagram in book) Used to identify substances in a mixture e.g. dyes in food colouring.

Question 40

Gas chromotography

Answer 40

(See diagram in book) Used to identify elements in a substance. It is better to use machines for identifying substances as they are quicker, more accurate, and can detect smaller amounts.