1
Q
What are the states of matter?
A
solids
liquids
gases
2
Q
solids
A
- there are strong forces of attraction between particles
- particles don’t move so all solids keep a definite shape
- particles vibrate about their position
3
Q
liquids
A
- weak forces of attraction between particles
- particles move freely but stick closely together
- don’t keep a definite shape
4
Q
gases
A
- very weak forces of attraction between particles
- particles move freely and are far apart
- don’t keep a definite shape or volume
5
Q
solid ~> liquid
A
melting
6
Q
liquid ~> gas
A
evaporating
7
Q
gas ~> liquid
A
condensating
8
Q
liquid ~> solid
A
freezing
9
Q
solid ~> gas
A
subliming
10
Q
Diffusion
A
the gradual movement of particles from an area of high concentration to an area of low concentration
11
Q
solution
A
is a mixture of a solute and a solvent that does not separate out
12
Q
solute
A
the substance being dissolved
solute - solid
13
Q
solvent
A
the liquid it’s dissolving into
14
Q
saturated solution
A
a solution where the maximum amount of solute has been dissolved; so no more solute will be dissolved in the solvent
15
Q
protons
A
-heavy
-positively charged
16
Q
neutrons
A
- heavy
- neutral
17
Q
electrons
A
- have hardly any mass
- negatively charged
18
Q
nucleus
A
- middle of atom
- contains protons and neutrons
- positive charge
- almost whole mass of atom is concentrated in nucleus
19
Q
electrons
A
- move around the nucleus in shells
- negatively charged
- have no mass
20
Q
how many electrons can the first 3 shells hold?
A
2, 8, 8
21
Q
number of protons and nr of electrons…
A
is equal
22
Q
if electrons are added or removed, the atom becomes charged and is then
A
an ION
23
Q
atomic number
A
indicates how many protons there are
24
Q
atoms of the same elemet all have the same number of…
A
protons
25
mass number
total of protons and neutrons in the atom
26
to get the number of neutrons…
subtract the atomic number from the mass number
27
isotopes
different atomic forms of the same element, which have the same number of protons but different numbers of neutrons
28
example of pair of isotopes
Carbon-12 and carbon-13
29
elements
consist of one type of atom only
30
compounds
substance that is made of two or more different elements which are chemically bonded
31
give an example of a compound
carbon dioxide; 1 carbon atom + 2 oxygen atoms
32
properties of compounds are...
...totally different form the properties of the original elements
33
mixtures
- are not pure substances
- no chemical bond between the different parts of a mixture
- easily separated
- parts can be separated out by physical methods e.g. distillation
34
properties of mixtures
are a mixture of the properties of the separated parts
35
pure substances
- completely made up of a single element or compound
- have a specific, sharp melting point and boiling point
36
freezing point of water
o degrees Celsius
37
boiling point of water
100 degrees Celsius
38
when does a mixture boil or melt?
a mixture is not pure and will melt or boil gradually over a range of temperatures
39
filtration
is used to separate an insoluble solid forma liquid
40
carry out a filtration
- put a filter paper into a funnel and pour the mixture into it
- the liquid part of the mixture runs through the paper, leaving behind a solid residue
41
crystallisation
separates a soluble solid form a solution
42
how to crystallise a product:
1. pour the solution into an evaporating dish + heat it (water will evaporate and solution more concentrated)
2. once some water has evaporated + crystals form, remove dish + leave solution to cool
3. salt forms crystals as its insoluble in the cold
4. filter the crystals out of solution + let them dry in a warm place (drying oven or desiccator cold be used)
43
what is filtration and crystallisation used for?
separate rock salt, which is a mixture of salt and sand (compound) - but salt dissolves in water and sand doesn't
44
filtration and crystallisation
1. Grind up the rock salt with a pestle and mortar
2. Dissolve in beaker and stir
3. Filter through filter paper in a funnel
4. sand stays as big grains, which wont fit through the tiny holes in the filter paper
5. Evaporate in an evaporating dish
6. crystals form
45
chromatography
separate out mixtures
46
Rf value
ratio between the distance travelled by the dissolved substance (solute) and the solvent
46
paper chromatography practical
1) draw line with pencil at bottom of filter paper above the surface of the solvent
2) add different ink spots to the line
3) place the sheet into a beaker of solvent
4) place a lid on top of the container
5) solvent moves up the paper, carrying the inks with it
6) different dyes will move up the paper at different rates depending on their solubility
7) take the paper out + let it dry
8) end result is a pattern of sports called chromatogram
47
formula to find the Rf value
48
distillation
used to separate mixtures that contain liquids
49
simple distillation
used to separate out solutions
50
fractional distillation
used to separate a mixture of liquids
51
what is the relative mass of a proton?
1
52
what is the relative mass of a neutron?
1
53
what is the relative mass of an electron?
1/2000
0.0005
54
what is the relative charge of a proton?
+1
55
what is the relative charge of an electron?
-1
56
what is the relative charge of a neutron?
0
57
A = fractionating column
B = condenser
58
what happens to the shape of solids when they are heated?
the hotter the solid becomes, the more they vibrate causing solids to expand slightly
59
HCI
hydrochloric acid
60
what sort of substances are elements?
pure substances
61
what is a pure substance?
a substance is pure if it's completely made up of a single element or compound
62
simple distillation practical
1) heat the solution so the part of the solution with the lowest boiling point evaporates
2) the vapour is cooled, condenses and is collected
3) rest of the solution is left behind in the flask
63
what can simple distillation be used for?
to get pure water from seawater; water evaporates and the salt is left in the flask
64
give 3 examples of physical techniques how mixtures can be separated out
- filtration
- crystallisation
- distillation
Chemistry IGCSE
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