c1a revisionnotes jw

8/2/2019 C1a Revisionnotes JW

1/20J Wilkinson Page 1

C1a Revision Notes



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



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)



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



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



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



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



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



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



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.



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



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



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



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



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



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



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



*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



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


20/20

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).

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