Chemistry Unit 1

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  • Created by: Sav
  • Created on: 27-05-13 18:26
Mass Number
Number of Protons + Neutrons
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Atomic Number
Number of Protons/Electrons
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Elements
Substance that consists of 1 type of atom
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What decides what type of atom it is?
Number of protons in the nucleus
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Group 1 & 2
Reactive Metals
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Where in the PT are Noble Gases and what are they?
Group 0 - full outer shell so unreactive e.g. Argon, Neon, Helium
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Ionic Bonding
One atom gives an electron, becoming a positive ion, the other receives, becoming a negative ion. They are the attracted to eachother Usually occurs between a metal and non-metal atom
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Covalent Bonding
Each atom shares an electron with another atom - they must make enough C. bonds to fill outer shell. Generally occurs between 2 metal atoms
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Molecule
Combination of more than one of the same atom that has bonded e.g. O2
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Compound
Molecules that contain more than one type of element e.g. H20
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Elemet
Basic substance that can't be simplified e.g. Hydrogen
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Atom
Smallest amount of anelement
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Formula for Thermal Decomposition of Limestone
CaC03 -> CaO + C02
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What is Calcium Hydroxide & What can it be used for?
An alkali; neutralises acidic soil, can be used to test for Co2 as Limewater turns cloudy if there is CO2 because CaC03 is formed
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How is cement created?
Powdered limestone heated in a kiln with powdered clay
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How is mortar (sticks bricks together) created?
Cement is mixed with sand and water
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How is concrete made?
Mix cement with sand, water and gravel
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4 issues of Limestone Quarrying
1. Ugly holes, noisy and dusty. 2. Destroys habitats. 3. Limestone must be transported - more pollution. 4. Waste produced
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What is Quicklime?
Calcium oxide (CaO), created from heating limestone (thermal decomposition)
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What is Slaked Lime/Limewater?
Calcium Hydroxide (Ca(OH)2), is an alkali formed when CaO reacts with water (Ca(OH)2 + CO2 -> CaCO3 + H2O)
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3 reasons why we use/advantages of Limestone
1. Used in houses, roads, medicines, paints. 2.Neutralises acidic soil. 3. Neutralises sulphur dioxide in power stations
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5 advantages of Limestone
1. Cheaper than other rocks - widely available. 2. Quite attractive. 3. Doesn't rot/corrode - lasts long. 4. jobs/economy. 5. Usually area is landscaped/turned in a recreational facility after.
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Why is Limestone damaged by acid rain?
CaCO3 reacts with acid to form a salt, CO2 and H2O
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When you heat a carbonate and an acid, what is always produced?
The salt of it, H2O and CO2
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Word and Formula equations for when calcium carbonate reacts with sulfuric acid
CaCO3 (limestone/calcium carbonate) + H2SO4 (sulphuric acid) -> CaSO4 (calcium sulphate) + CO2 (carbon dioxide) + H2O (water)
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When Magnesium/Copper/Zinc (group 1 metals) and sodium carbonate is heated (thermally decomposed), what is always produced?
CO2 and the oxide of the carbonate e.g. Magnesium Oxide
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Formula for Sulphuric Acid
H2SO4
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Formula for hydrochloric Acid
HCl
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Nitric Acid
HNO3
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Metal Ore metal
Rock containing enough of a metal to make extraction worth-it; usually an oxide of that mleta
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What does profibility of metal extraction depend on?
1. Metal price. 2. Technology improvements
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What is Bauxite?
The main aluminium ore - aluminium oxide
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A metal that is found as the metal itself because it is unreactive
Gold
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3 ways of metal extraction
1. REDUCTION with carbon. 2. ELECTROLYSIS. 3. DISPLACEMENT reaction
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Metals higher than Carbon in the reactivity series are extracted using -
Electrolysis
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Metals below Carbon in the reactivity series are extracted using -
Reduction because Carbon can only take oxygen away from less reactive metals
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Reduction
Oxygen is removed from the ore (moves in the equation) therefore the metal is left on its own
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Electrolysis
Breaking down a substance using electricity. Electrons are given away by the negative cathode and taken away by the positive anode. Ions gain/lose electrons becoming atoms or molecules and are released
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Electrolyte
A liquid required in electrolysis to conduct electricity - has free ions
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Describe how electrolysis is used to get copper
1. Electrons are pulled off copper at the anode causing them to go into the solution as + copper ions. 2. They gain electrons near cathode and turn back into copper atoms. 3. Impurities dropped at anode as sludge and PURE copper atoms bond 2 cathode
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Anode
Lump of impure copper which will dissolve
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Cathode
Starts as a thin piece of pure copper but grows
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Displacement
A reactive metal is put into a solution of dissolved metal compound ad the reactive metal replaces the less reactive metal. Reactive metal bonds to non-metal ad pushes out less reactive metal.
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What happens if the more reactive metal is already in the solution in Displacement?
Nothing.
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Negatives of Metal Extraction
Bad 4 environment: noise, habitats, eyesore & deep mine shafts = dangerous. Mining & extracting burns fossil fuels
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3 Positives of recycling metals
1. Saves money & doesn't use much energy. 2. Conserves metal sources. 3. Less landfill
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2 common metal properties
1. Conduct Electricity and heat. 2. Can be bend into shape
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Properties of copper
Good conductor, hard and strong, can be bent, doesn't react with water
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Aluminium properties
Corrosion resistant, not too strong, low density and forms strong alloys
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Titanium properties
Very strong, corrosion resistant, low density
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an alloy
2 metals or a metal and a non-metal joined together. They're harder than pure metals
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Layers of the earth
Inner core - solid (iron & nickel). Outer core - liquid (iron & nickel). Mantle - solid rock but hot enough to flow. Crust - thin, made of tectonic plates.
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Continental Drift
Mantle moves due to convection currents caused by radioactive decay in the core. The world used to be one continent
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How has the Earth's atmosphere changed?
Violent volcanic activity created a mixture of CO2, Ammonia and Methane. Photosynthesis - CO2 -> oxygen. Oxygen then converted ammonia and methane to nitrogen and CO2
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What does the Earth's atmosphere consist of now?
Mostly nitrogen, some oxygen, less CO2, only 2% noble gases
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Use of Helium (noble gas)
It's light therefore airships and in balloons
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Use of Neon (noble gas)
Advertising because it glows when an electric current is passed through it
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Argon
In light bulbs because it prevents the hot filament from reacting with the air and burning away
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What does the Carbon (or Nitrogen/water) cycle show?
Shows how carbon moves between atmosphere, rock and oceans
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Name some parts of the Carbon Cycle
Death & respiration of living creatures, photosynthesis and death (decomposition to organic compounds) of plants, combustion of fossil fuels, industry
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What is Crude Oil and how is it formed?
Fossil fuel: most important resource, formed from dead organic material
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Exothermic Reaction
Heat is produced
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Saturated
Unhealthy as increases amount of cholesterol in blood, alkAnes, no double bond
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Unsaturated
Healthy as reduces amount of cholesterol in the blood, alkEnes, there is.a double bond
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Animal Fats
Solids, mainly saturated hydrocarbons
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Vegetable Oils
Liquids, mainly unsaturated hydocarbons
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Hydrogenation
Adds hydrogen (hardening) - making double bond - makes it more solid, therefore has a higher melting point. Usually only hydrogenate SOME so only SOME become double
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Partially hydrogenated vegetable oils: good or bad?
Cheaper and keep longer BUT you end up with transfats which are bad for you
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What are emulsions made up of?
Lots of droplets of 1 liquid suspended in another. 2 substances mixed together, usually contain emulsifiers.
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Examples of emulsifiers
Mayonnaise, ice cream
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Hydrophobic and Hydrophilic e.g's
Oil - phobic, water - philic
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Pros of emulsifiers
Longer shelf-life, allows food companies to produce food lower in fat but same texture
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Con of emulsifiers
Some people are allergic to the emulsifiers
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3 Uses of food additives
improve appearance, improve taste, prolong life
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4 types of food additives
flavourings, preservatives, colourings and anti oxidants
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What is the use in E numbers?
Identification
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How do you test what food colourings are in the food?
Seperation technique using chromatography paper as they rise up at different lengths due to mass + density
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Standard
plain colours
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Plastics are made from
Crude Oil
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ALL fractions of crude oil are
alkAnes, they can become alkEnes later
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Why do all crude oil fractions keep their own properties?
They aren't chemically bonded together. It is a mixture of saturated hydrocarbons
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Hydrocarbons
Fuels e.g. petrol + diesel
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Crude oil origins
found under the sea bed
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How is crude oil separated out?
Fractional distillation: different alkAnes have different boiling points
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The smaller the molecule...
the lower the boiling point, the less viscous it is, the more flammable it is
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What is a fraction?
A mixture of about 4 substances
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What can longer molecules be used for?
Lubricants - keep parts of car engines stuck together
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Cracking
used to break large hydrocarbons down - heating usually with a catalyst. Produces a new smaller alkAne (fuels) and a new small alkEne (plastics).
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Describe what happens in a fractioning column
Crude oil is heated to extreme temperatures and rises and vapourise . The biggest molecules condense first
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How many bonds must each Carbon have?
4
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How many bonds must each Hydrogen have?
1
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What does satuated mean?
e.g. Carbon has as many hydrogen atoms attached to it as possible
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Polymerisation
AlkEnes undergo this process, lots of small alkEne molecules called Monomers join together (under pressure) to form a large molecule called a Polymer
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What 3 things to a polymers properties depend on?
1. What it is made from. 2. The Temperature and 2. the pressure of POLYMERISATION
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Uses of polymers
Smart material: memory foam. New biodegradable packaging being produced. Cornstarch, plastic bags, waterproof fabric coatings, tooth fillings, wound dressings
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Cons of polymers
Most aren't biodegradable, hard to dispose of so must reuse/recycle, relatively cheap BUT come from crude oil so gettig more exp
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EthAne -> Polythene. What us poly(e)thene?
a polymer that is saturated despite its name. Polymers can only be made from alkEnes
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General formula for alkAnes
CnH2n+2
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First 4 AlkAnes and their formulas
1. Methane (CH4) 2. Ethane (C2H6) 3. Propane (C3H8) 4. Butane (C4H10)
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General formula for alkEnes
CnH2n
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First 2 alkEnes
1. Ethene (C2H4) 2. Propene (C3H6)
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Volatility
How reactive it is/it's boiling point: helps decide its use
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How is ethanol produced?
EthAne reacts (is hydrated) with steam to produce ethanol in the presence of a catalyst
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Is this process to produce ethanol expensive?
Cheap and not much is wasted BUT ethanol comes from crude oil which is NON-RENEWABLE therefore it will become more expensive
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How can ethanol be produced from renewable sources?
FERMENTATION: sugar -> carbon dioxide + ethanol
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Pros and Cons of the process of finding ethanol by Fermentation
Pros: sugar (the raw material) is renewable, ethanol can be used as a cheap fuel. BUT it isn't very concentrated ethanol so needs to be distilled and purified
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AlkAnes burn to produce
CO2 and H2O except if the oxygen/air supply if limited, then you get CO or C and H2O
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when a alkAne is burned in plentiful oxygen it is called
complete combustion
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How can you get hydrocarbons from plants?
Crush the plant material, press this material between metal plates, CENTIFUGE seperates oil out from the material, Distillation
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What are plant oils
unsaturated/alkAnes used for cooking or as a fuel. Tend to be liquid
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pros of plant oils
Better than cooking with water because: higher boiling points, diff flavour, carries the flavour, increases energy in food. Provide lots of energy, lots of nutrients, contain ESSENTIAL fatty acids
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A fuel made from Plant Oils
biodiesel
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Other cards in this set

Card 2

Front

Number of Protons/Electrons

Back

Atomic Number

Card 3

Front

Substance that consists of 1 type of atom

Back

Preview of the back of card 3

Card 4

Front

Number of protons in the nucleus

Back

Preview of the back of card 4

Card 5

Front

Reactive Metals

Back

Preview of the back of card 5
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