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8/2/2019 C1a Revisionnotes JW
1/20J Wilkinson Page 1
C1a Revision Notes
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Atoms Molecules
Element
A substance made of only one type of atom
e.g. or
Compound
A substance made of more than one type of atom bonded together.
e.g.
Chemical Symbols
Atoms are represented by chemical symbols
O 1 oxygen atom H 1 hydrogen atom
C 1 carbon atom Na 1 sodium atom
Ca
1 calcium atom Fe
iron atom
Electrons
Nucleus
Two or more atoms bonded (stuck)
together.
e.g.
They share or swap electrons
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Chemical Formulas
Molecules have chemical formulas
e.g.
H2 hydrogen molecule (2 hydrogen atoms bonded)
O2
Oxygen molecule (2 oxygen atoms bonded)
CaCO3 Calcium carbonate molecule (1 calcium atom, 1 carbon atom and
3 oxygen atoms)
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Periodic Table
A list of all the elements (your journal contains the real one)
Group A column. All elements in one group behave the same way (they
have similar properties).
4
Group
1Group
2
3 50
6 7
Transition metals
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Limestone
A rock
Also called calcium carbonate (CaCO3)
Uses of limestone
Making glass
Building blocks
Making cement
Making quicklime
For making slaked
lime
For making lime mortar
For making limewater
For making
concrete
1
2
3
4
5
6
7
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1 Recipe for Quicklime
Limestone quicklime + carbon dioxide
Calcium carbonate calcium oxide + carbon dioxide
CaCO3 CaO + CO2
2 Recipe for slaked lime
Quicklime + water slaked lime
Calcium oxide + water calcium hydroxide
CaO + H2O Ca(OH)2
Quicklime
(calcium oxide)
Carbon dioxide
Limestone
(calcium carbonate)
Thermal decomposition calcium carbonate
breaks down into calcium oxide and carbon
dioxide when it is heated.
quicklime
water
Slaked
lime
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3 Recipe for Limewater
Test for carbon dioxide:- Calcium hydroxide reacts with carbon dioxide to make
calcium carbonate which makes the limestone milky
4 Recipe for lime mortar
limewater
Slaked lime
(calcium
hydroxide)
water
Slaked lime (calciumhydroxide)
Sand
Water
Lime mortar
Brickmortar
The calcium hydroxide reacts with carbondioxide in the air to make hard calcium
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5 Recipe for cement
6 Recipe for Concrete
7 Recipe for Glass
Cement
SandWater
concrete
Gravel
limestone
Sand Sodium carbonate
(soda)
Glass
Heat
ClayLimestone
Heat
Mortar made with cement and sand will set
under water! It is stronger and sets faster
than lime mortar
cement
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Thermal Decomposition of Carbonates
Nearly all metal carbonates are broken down by heat to give a metal oxide andcarbon dioxide. (Sodium carbonate and potassium carbonate dont
do this).
e.g.
calcium carbonate calcium oxide + carbon dioxide
Heat Breaks down
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Extracting Metals
Ore Rock containing a metal or metal compound.
- It contains enough to make it worth extracting the metal
(extracting means getting the metal out of it)
Reactivity
Metals and carbon (not a metal) are often listed in a reactivity series.
Note Learn the facts not the list (if you need the list it will be printed
in the question)
Potassium
Sodium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Tin
Lead
Copper
Silver
Gold
Platinum
Most reactive
Least reactive
Metals more reactive than carbon
are extracted from ores by
electrolysis.
Metals less reactive than carbon are
extracted from ores by reduction.
Very unreactive metals can be found
in the ground in their native state.
This means gold or platinum can be
found as pure metal rather than as
ore.
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Extracting a Metal by Reduction
The metal compound in an ore is a metal oxide a metal bonded with
oxygen (e.g. iron oxide, zinc oxide).
Carbon is more reactive than the metal, so the carbon steals the oxygen from
the metal.
OR
(in scientific terms)
The metal is displaced from its oxide by carbon.
OR
The metal oxide is reduced (its oxygen is taken away).
Extracting Iron by Reduction
Metal ore
(metal oxide)
Heat with carbon
metal
Carbon dioxide
Blast
furnace
Iron oxide
Coke
It is carbon
It reduces iron
oxide
It burns to heat
the furnace
Limestone
Removes
impurities
Carbon reduces the iron
oxide to leave iron
Or
Carbon displaces iron from
iron oxide
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Pure Metals and Alloys
(Properties = how it looks or behaves)
Each alloy has its own properties, so each has different uses.
Properties that can change:-
o Strengtho Appearanceo Hardnesso Resistance to corrosion ( corroding is like rusting)
Smart alloys
o Also called shape memory alloyso If you bend them they go back to the correct shape (used in
braces for teeth)
Pure Metal Alloy
Pure Metal
Alloy
(has different properties
compared to pure metal)
Mix in other elements
Different Alloy
(with its own properties)
Mix in different
elements or different
amounts
Atoms in regular layers.
Layers can slide over each
other bendy, soft
Metal atom Atom of another
element
Layers out of shape so
cant slide easily over each
other harder metal
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Alloys (Continued)
Steels = alloys of iron
Pure Iron
(soft, bendy)
High alloy steels
e.g. stainless steel
which wont rust
Low alloy steels
Carbon steels
(Harder, but more
brittle)
Add over 5% of
other metals
Add up to 5% ofother metals
Add up to 1.5% of
carbon
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Transition Metals
Good conductors of heat
Good conductors of electricity
Strong
Hard
Dense (heavy)
Can be bent or hammered into shape
High melting points (except mercury which is a liquid)
Copper
A very useful transition metal
Used for water pipes in houses because:-
o Bends to shapeo Does not corrode
Used for electrical wires because:-
o Good conductor of electricityCopper ores are running out and a lot of energy is needed to extract copper
so
new ways of extracting copper are being developed (using bacteria, fungi and
plants)
Transition Metals
Periodic table
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Aluminium and Titanium
Both metals are useful because:-
o they have low densities (lightweight)o they resist corrosion
Both are expensive to extract because a lot of electricity is needed.
Uses of Aluminium Uses of Titanium
Cans Jet engines strong at high
Foil Nuclear reactors temperatures
Electricity cables (on pylons) hip joints (strong and light)
Aircraft bikes
Aluminium
Titanium
Aluminium
Titanium
Start to
corrode
Corrosion forms a tough oxide layer
which protects the rest of the metal so
it does not corrode
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Crude Oil and Hydrocarbons
Crude Oil
A mixture of many compounds mainly alkane hydrocarbons
Hydrocarbons
There are many different ones
Each is
o A chain of carbon atomso Surrounded by hydrogen atoms
Examples
If you know how many carbon atoms are in the molecule you can work out
how many hydrogen atoms there are
e.g. C2H6
C C
H H
H H
H H
2 carbon atoms and
6 hydrogen atoms
Formula C2H6
CC C
H H
H
H H
C
H H
H
H H
4 carbon atoms and
10 hydrogen atoms
Formula C4H10
X2 then +2
i.e. (2X2) +2 = 6
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Separating Crude Oil
Crude oil is separated into fractions by fractional distillation
A fraction is made of molecules with similar boiling points
Short chain hydrocarbons low boiling points
Long chain hydrocarbons high boiling points
Fractional Distillation
Crude oil is heated and goes in as vapour
Hot vapours rise and cool
Different fractions turn to liquids (condense) at different temperatures
and are collected.
1
2
3
1
2
Fractionating column
Tar
3
Petroleum Gas
Petrol
Kerosene
(aircraft fuel)
Diesel
Heated crude oil
hot
cool
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*Viscous gooey, sticky (syrup is viscous)
Short Chain
Hydrocarbon
(a few carbon
atoms)
Long Chain
Hydrocarbon
(Many carbon
atoms) Viscous *
Runny Burn easily
(used as fuels)
Difficult to
burn
Low boiling
point
High boiling
point
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Burning Hydrocarbons
Burning any pure hydrocarbon in plenty of air produces :-
Carbon dioxide and
Water
Dissolves inwater droplets
in the air
Burning
hydrocarbon
fuel
Carbon
dioxide a
greenhousegas
Global
warming
water
Carbon
monoxide
Poisonous
Particles
of carbon
Health
problemsThey reflect
sunlight back
into space
Global Dimming
Sulfur
dioxide
Acid
rain
In a lot of air
In a little air
Sulfur impurities in
fuel
Note :- Sulfur compounds can be removed from the fuel before burning the fuel
or
Sulfur dioxide can be removed from waste gases after burning the fuel
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New Fuels
Traditional fossil fuels are running out and causing pollution
Biofuels
New fuels from plants
Cause less pollution
Ethanol
o Made from plant sugarso Added to petrol (gasohol)
Biodiesel made from plant oils
They dont make global warming worse because all the carbon dioxidefrom burning these fuels is re-used by the next crop as it grows
(photosynthesis).