Chemistry

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What is an atom?
A very small particle
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What is an atom made up of?
Protons, neutrons and electrons
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What is an element?
A substance that contains only one type of atom
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How many elements are there?
About 100
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How is and element represented?
By a chemical symbol
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How are elements arranged?
In the Periodic Table, in order of atomic number
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What do the groups in the periodic table contain?
Elements that have similar properties
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What are the group 1 elements?
Alkali Metals
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When the group 1 elements react vigorously with water what do they produce?
An alkaline solution and hydrogen gas
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When group 1 elements react rapidly with oxygen what do they form?
Metal Oxide
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What are group 0 called?
The Noble Gases
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Why are all group 0 unreactive?
Because their atoms have full outer shell (they are stable)
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How many electrons are there in a full outer shell?
8 electrons except helium which only has 2
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What has electrical charges?
Protons, neutrons and electrons
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What are the electrical charges of protons, neutrons and electrons?
Proton +1, Neutron 0 and Electron -1
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Why do atoms as a whole have no overall charge?
Because the contain an equal number of protons and electrons
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What is the number of protons in an atom called?
Atomic Number
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What is the mass number?
The sum of the protons and neutrons in an atom
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How are the neutrons calculated?
Mass Number - Atomic Number
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What is the maximum amount of electrons in the first shell?
2
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What does the electron configuration tell us?
How the electrons are arranged around the nucleus in the shells
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How are the groups arranged in the periodic table?
In terms of electronic structure
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What do elements in the same group have?
Same number of electrons in their outer shell and this gives them similar chemical properties
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What is a compound?
When elements react their atoms join with other atoms
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When elements react their atoms join with other atoms what does it involve?
The giving and taking of electrons to form ions or sharing of electrons to form molecules
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How are compounds represented?
By a combination of numbers and chemical symbols called a chemical formula
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What do chemical formulas show?
The different elements in a compound and the number of atoms of each element in the compound
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How can you show what is happening during a chemical reaction?
Writing a word/symbol equation
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What is a reactant?
A substance that reacts
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What is a product?
A new substance that is formed
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What must chemical symbol equations always be?
Balanced
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What is the chemical symbol for limestone?
CaCO3
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What is limestone?
It is a sedimentary rock consisting mainly of calcium carbonate
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What is good about limestone?
It's cheap, easy to obtain and has many uses
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What can limestone be used for?
Building materials and making cement, motar and concrete
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What erodes limestone?
Acid rain
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When calcium carbonate is heated in a kiln why happens?
The limestone decomposes (thermal decomposition)
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What happens during thermal composition of limestone?
The calcium carbonate brakes down into calcium oxide and carbon dioxide
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How does Calcium Hydroxide prevent crop failure?
Calcium Hydroxide neutralises the soil and lakes
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How do you make cement, motar and limestone?
Powdered limestone is roasted in a rotary kiln with powdered clay to produce dry cement. when sand and water is is mixed in, motar is produced. When aggregate, sand and water are mixed in, concrete is formed
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When carbonates react with dilute acids what is formed?
Carbon dioxide
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What colour does limewater turn when carbon dioxide is mixed in?
Milky white
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What does the earths crust contain?
Naturally occurring elements and compounds called minerals
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What is a metal ore?
A mineral that contains enough metal to make it economically viable to extract
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What happens before metals are extracted and purified?
The ores are mined and impurities may be removed
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What does the method of extracting metals depend on?
How reactive the metal is
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What are most metals found as?
Metal oxides
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How are metals less reactive than carbon extracted from their oxides?
By heating with carbon
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How are metals more reactive than carbon extracted from their oxides?
By electrolysis of molten compounds
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Why is copper useful?
It is a good conductor of electricity and heat, it is easily bent into shape but hard enough to be used to make water pipes and tanks.
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How is copper extracted from copper-rich ores?
By heating the ores in a furnace. (Smelting)
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How is copper purified?
Electrolysis
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How can copper be obtained?
From solutions of copper salts by electrolysis or by displacement using scrap iron
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What happens during electrolysis?
The positive copper ions move towards the negative electrode and form pure copper metal
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What are the new methods of extracting copper from its ores?
Low grade ores (ores that contain small amounts of of copper) OR contaminated land by phytomining and bioleaching.
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What is phytomining?
It is a method that uses plants to absorb copper. As plants grow they absorb and store copper.the plants are then burned and the ash produced contains copper in relatively high quantities
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What is bioleaching?
It uses bacteria to extract metals from low-grade ores. A solution containing bacteria is mixed with low -grade ore. The bacteria convert the copper into solution ( known as a leachate solution) where it can be easily extracted
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How do you produce iron?
Iron oxide is reduced in a blast furnace.
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Molten iron obtained in a blast furnace contains roughly..?
96% iron and 4% carbon and other metals
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Why is impure iron no use?
It is brittle and has limited used
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How do we produce pure iron?
Remove all the impurities
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How are the atoms arranged in pure iron?
In layers that can slide over each other easily.
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What is good about pure iron?
It is soft,malleable, and it can be easily shaped
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How can the properties of iron be changed?
By mixing it with small quantities of carbon or other metals to make steel.
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What is steel?
An alloy
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What is an alloy?
A mixture of two or more metals OR a mixture of one metal and a non - metal
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What properties does steel with a big carbon content have?
Hard and strong
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What properties does steel with a low carbon content have?
Soft and easily shaped
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What properties does stainless steel have?
Hard and is resistant to corrosion
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What is between groups 2 and 3 on the periodic table?
The Transition Metals
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What are the properties of transition metals?
Good conductors of heat and electricity, they are hard and mechanically strong, they have high melting points (exempt mercury) and they can be bent or hammered into shape
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How are titanium and aluminium extracted from their ores?
Electrolysis
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Why is electrolysis expensive?
It has many stages and required a lot of energy.
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What is copper useful for?
Chemical wiring and plumbing
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What are the properties of aluminium?
It is resistant to corrosion and has a low density so it is very light
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What is aluminium useful for?
Drink cans, window frames, lightweight vehicles and aeroplanes
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What are the properties of titanium?
Strong and is resistant to corrosion
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What is useful for?
Airplanes, nuclear reactors and replacement to hip joints
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Why should we recycle metal?
To save money/energy, to make sure natural resources aren't used up and reduce damage to the environment
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what is a mixture?
Two or more elements or compounds not chemically combined together
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How can a mixture be separated ?
By distillation?
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What do most of the compounds in crude oil consist of?
Hydrogen and carbon (hydrocarbons)
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What are the properties of large hydrocarbons?
Less volatile, les easily ignited, higher melting point and has a less easy flow.
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How is crude oil separated into parts?
Fractional distillation
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What is a biofuel?
A fuel that are produced by plant material
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Give two examples of biofuels
Biodiesel and ethanol
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What is the spine of hydrocarbons made up of?
Chain of carbon atoms
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What are hydrocarbon chains joined together?
Single carbon-carbon bonds
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A single carbon-carbon bond is known as what?
An Alkane
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What is the simplest alkane?
Methane
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What is the general formula for an alkane?
CnH2n+2
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Is and alkane saturated or unsaturated?
Saturated
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Why is there a greater demand for alkanes as a fuel?
Shorter-chain hydrocarbons release energy more quickly by burning
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What do many fuels contain?
Hydrogen, carbon and sulphur
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What happens during combustion of hydrocarbon fuel?
Both carbon and hydrogen are oxidised
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Due to the high temperature reached when fuels burn, nitrogen in the air can react with what?
Oxygen to form nitrogen oxides e.g sulphur dioxide
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What do solid particles in the air cause?
Global dimming
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How can sulphur dioxide be removed form waste gases after combustion by what?
Power stations
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What does cracking involve?
Heating the hydrocarbons until they vaporise and then passing the vapour over a hot catalyst
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Explain cracking
When longer-chain hydrocarbons can be broken down into shorter, more useful hydrocarbons
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What reaction takes place during cracking?
Thermal decomposition
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What bond does and alkane have?
A double carbon-carbon bond
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What is the general formula for an alkene?
CnH4
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What is Ethernet made up of?
4 hydrogen atoms and 2 carbon atoms
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How can alkenes be represented?
By a display formula
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What is ethanol?
Alcohol
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How can ethanol be produced?
By reacting the alkene Ethene with steam in the presence of a catalyst, phosphoric acid
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What is another way ethanol can be produced?
By fermentation or sugar
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What happens during fermentation of sugar?
Sugar is converted into ethanol and carbon dioxide
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What are alkenes useful for making other than molecules?
Polymers (long-chain molecules)
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What is polymerisation?
When small alkene molecules (monomers) join together to form polymers
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What are all plastics?
Synthetic polymers
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Why are polymers not biodegradable?
Because they can't be broken down by microbes
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What are polymers useful for?
Implanting materials are used for tissue surgery, dental cement and as wound dressings
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What is good about plastics?
It's cheap and easy to produce
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Why is burning plastics bad for the environment?
Because it releases CO2 which contributes to global warming
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What are two ways of disposing plastics?
Burning and landfill sites
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What do some plastics produce if they are burned?
Toxic fumes
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What are plants such as nuts, seeds and fruits rich in?
Oil
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How can the oil be extracted from the plant materials?
By pressing them and by distillation
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What do the processes of distillation and pressing remove?
Water and other impurities from the plant material
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Why are vegetable oils important foods?
Because they provide you with nutrients and energy
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What can vegetable oils also be used for?
Fuels in converted cars instead of petrol/diesel
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What bonds does vegetable oils contain?
Double carbon-carbon bond
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Are vegetable oils saturated or unsaturated?
Unsaturated
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How do you test if a vegetable oil is saturated or unsaturated?
With bromine water
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Why are vegetable oils used for cooking?
Because they have a higher boiling point so it can be used to cook foods at higher temperatures and a different flavour is added to the food
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What does cooking with vegetable oils increase?
The energy that the food releases when it is eaten
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If there are more Double carbon-carbon bonds in a substance what is lower?
The melting point
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What melting point do unsaturated fat tend to have?
Below room temperature
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How can the melting point of an oil be raised above room temperature?
By removing the carbon-carbon bonds
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If you have removed the carbon-carbon bonds from oil, what do you get?
A solid e.g. Margarine
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What are the advantages of hardens oil?
It's spreadable and can be used to make cakes and pastries
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What is the hardening process of oil called?
Hydrogenation
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Explain the process of hydrogenation
The unsaturated fat is heated with hydrogen at about 60 C, in the presence of a nickel catalyst
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When the reaction of hydrogenation takes place what is removed?
The double carbon-carbon bond
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What is produced when oil is miked with water?
An emulsion
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What are the properties of emulsions?
Better textures, better appearance and better coating ability
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What uses do emulsions have?
Salad dressings, cosmetics, paints and ice cream
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What is an emulsifier?
A substance that helps to stabilise an emulsion
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What is hydrophilic?
The head that mixes with water molecules (water loving)
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What is hydrophobic?
The tail that mixes with oil molecules (water taking)
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What is the layered structure of the earth consist of?
Crust, mantle, core (made up of nickel and iron)
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What is the rock cycle?
When rocks at the earths surface are continually being broken up, reformed and changed in an ongoing cycle of events
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Who proposed the theory of continental drift?
Alfred Wegener
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What evidence is there of the continental drift?
Closely matching coastlines, fossils of the same animals and the continents fit together like a jigsaw piece
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What is the earths lithosphere cracked into?
Tectonic plates
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What causes the tectonic plates to move?
Intense heat, is released by radioactive decay deep in the earth, creates convection currents in the mantle
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What is a common occurrence on plate boundaries?
Earthquakes and volcanic eruptions
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What two scientists tried to test one possible theory of how life began?
Miller and Urey
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What chemicals did Miller and Urey they mix together?
Water, methane and ammonia.
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What did they use to represent lightning?
Sparks (electrical discharges)
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What does the primordial soup theory show?
An explanation of how life began
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What does intense volcanic activity release?
Carbon dioxide, water vapour and small proportions of methane and ammonia
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How is there more CO2 on the earth today?
Because of volcanic activity and burning fossil fuel
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How much (in percentage) oxygen and nitrogen is in the atmosphere?
20% oxygen and 80% nitrogen
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how can different gasses be collected?
Cooling air into a liquid and heating it
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What Re the two main ways that CO2 is absorbed from the atmosphere?
Sedimentary rock and in oceans
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Which two gases is the atmosphere mainly made up of?
Oxygen and nitrogen
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Card 2

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What is an atom made up of?

Back

Protons, neutrons and electrons

Card 3

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What is an element?

Back

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Card 4

Front

How many elements are there?

Back

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Card 5

Front

How is and element represented?

Back

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