Chemistry Unit 1 Revision

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What is a nucleus?
It's in the middle of an atom. It contains protons and neutrons. The nucleus has a positive charge overall.
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What are electrons?
Move around the nucleus. They're negatively charged
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What are the charges of protons, neutrons and electrons?
Protons = Positively charged (+) Neutrons = no charge Electrons = negatively chagred (-)
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Why do atoms have no overall charged?
They're neutral because the number of protons equal the number of electrons. However if some if some electrons are added or removed, the atom becomes charged and is then an ion.
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What do elements constist of?
One type of atom. There are about 100 different elements. All the atoms of a particular element have the same number of protons, Different elements have atoms with different numbers of protons
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If elements are in the same column (groups) what does this mean?
Have similar properties because they have the same number of electrons in their outer shell
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What does the top number represent?
Mass Number = the total number of protons and neutrons
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What does the bottom number represent?
The atomic number = number of protons (the number of electrons)
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What are the electron shell rules?
The lowest energy level always holds 2 + the other shells can hold 8 electrons. Each atom wants a full out shell as they're stable
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What do compounds consist of?
Atoms join together to make compounds. Different elements react with other atoms to form compounds.
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What is ionic bonding?
When a metal and a non-metal bond. Due to a metal atom loosing an electron to form a positive ion, and the non-metal atom gains an electron to form a negative ion. This means that they're strongly attracted to each other.
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What is covalent bonding?
When non-metals bond. As they share electrons because each atom wants to make enough covalent bonds to fill up its outer shell
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Compounds formed from metals and non metals constist of...
ions
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Compouds formerd from non metals consist of....
molecules
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What is limestone mainly made of?
Calcium carbonate (CaCO3)
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What can calcium carbonate be used for?
Building and is obtained by quarring
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Calcuim carbonate can be decomposed by heating to make?
Calcium oxide and carbon dioxide
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Calcium oxide reacts with water to produce?
Calcium hydroxide which is an alkali that can be used in the neutralsiation of acids
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A solution of calcium hydroxide in water (limewater) reacts with CO2 to produce?
Calcium carbonate
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When a carbonate reacts with acid what does it produce?
Carbon Dioxide - A salt - Water
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How is cement made?
Limestone is heated with clay
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How is concrete made?
Cement is mixed with sand to make mortar and with sand aand aggregate to make cincret
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Advantages of limestone quarrying
Provides jobs - Brings money into the local economy (local improvements) - landscaping - restoration
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Disadvantages of limestone quarrying
Noise - Dust - Destroys habitats - Needs to be transported (noise and pollution) - unsightly tips
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What is a metal ore?
A rock which contains enough metal to make it worthwhile extracting the metal from it
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What is reduction with carbon?
Metals that are less reactive than carbon can be extracted from their oxides by reduction with carbon. Oxygen is removed from it
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What metals can be extracted with electrolysis of molten compounds?
Metals that are more reactive than carbon. However they use a large amount of energy meaning they're expensive
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Copper and electrolysis
Copper can easily be extracted by reduction with carbon (smelting), but the copper is impure. Electrolysis means that it's very pure (better conductor)
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Electrolysis definition
Is the breaking down of a substance using electricity.
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What happens at the anode and cathode/
Electrons are taken away by the (positive) anode and given away by the (negative) cathode. As ions gain or lose electrons they become atoms or molecules are released.
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Draw Electrolysis of copper?
.
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How can copper be extracted in a displacement reaction
If you put a reactive metal into a solution of a dissolved metal compound, the reactive metal will replace the less reactive metal in the compound.
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How is bioleaching used to extract copper?
Uses bacteria to separate copper from copper sulfide. The bacteria get energy from the bond between copper and sulfur, separating the copper. The leachate (the solution produced) contains copper with can be extracted (filtration)
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How is phytomining used to extract copper?
Growing plants in soil that contains copper. The copper gradually builds up in the leaves. The plants can then be harvested, dried and burned in a furnace. The copper can be collected from the ash left in the furnace.
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Why is metal extraction bad for the environment?
Noise. Loss of Habitat. Dangerous. Pollution and trafic
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Why should we recycle metals?
Extracting them uses limited resources and is expensive. Fossil fuels are running out. Recycling saves money. Cuts down metal sent to landfil.
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What are the elements in the central block of the periodic table known as?
The transition metals
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What are the main properties of transition metals?
Good conductors of heat and electricity. Strong (hard to break) but they can be bent and hammered into shape
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What are transition metals useful for?
Structural materials and for making things that must allow heat or electricity to pass through them easily.
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What are the properties of copper?
Good conductor of electricity. It's hard and strong but can be bent. It doesn't react with water
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What are the properties of Aluminium?
Is corrosion-resistant and has a low density.
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What are the properties of titanium?
Low density metal. It's very strong. Corrosion-resistant.
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Why does iron from the blast furnace have limited uses?
contains about 96% iron. The impurities make it brittle.
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What is iron converted into?
Steels. Steels are alloys since they are mixtures of iron with carbon. Some steels contain other metals.
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What steels are easily shapes?
Low carbon steels
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What steels are hard?
High carbon steels
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What steel is resistant to corrosion?
Stainless steel
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Why are pure copper, gold, iron and aluminium mixed with small amounts of similar metals?
They're too soft for many uses, so it makes them harder for everyday use if they're mixed with small amounts of similar metals
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What is crude oil a mixture of?
Hydrocarbons
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What does a mixture consist of?
2 or more elements or compounds not chemically combined together. The chemical properties of each substance in the mixture are unchanged. It is possible to separate the substances in a mixture by physical methods including distilation.
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What do most of the compounds in crude oil consist of?
Molecules made up of hydrogen and carbon atoms. Most of these are saturated hydrocarbons called alkanes
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What is the general formula of an alkane?
CnH2n+2
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Fractional Distillation of Crude Oil
Crude oil is split into separate groups of hydrocarbons by crakcing. The fractionating column works continuously, with heated crude oil piped in at the bottom. Various fractions are continuously tapped off at the different levels where they condense
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What happens to the vapours from crude oil?
Either passed other a hot catalyst or mixed with steam and heated to a very high temperatuer so that thermal decomposition reaction occurs
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What do the products of cracking include?
Alkenes (unsaturated hydrocarbons) and Alkanes (saturated hydrcarbons)
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What is the general formula of an alkene?
CnH2n
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How does an alkene react with bromine water?
Turns it from orange to colourless
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Alkenes have a double C=C bond. Draw Ethene ->
.
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When ethene reacts with steam, what does it produce?
Ethanol
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What influences how hydrocarbons are used?
The properties which depend on the size of the molecule
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What do most fuels contain?
Carbon and/or hydrogen and may also contain some sulfur.
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What are the gases released into the atmosphere when a fuel is burnt?
Carbon Dioxide. Water (vapour). Carbon Monoxide. Sulfur dioxide. Oxides of nitrogen.
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What does sulfur dioxide and oxides of nitrogen cause?
Acid Rain
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What causes global warming?
Carbon Dioxide
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What do solid particulates cause?
Global Dimming
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Sulfur can be removed from fuels before they are burned (vehicles). What else can sulfur be removed from?
The waste gases after combustion (power stations)
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How are biofuels produced?
Plant materials. Theree and economic, ethical and environmental issues surrounding their use
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What can alkenes be used to make?
Polymerisation. Polymers (such as poly(ethene) and poly(propene). In these reactions, many small molecules (monomers) join together to form very large molecules
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Draw the reaction of many ethene monomers joining to form poly(ethene)
.
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What are some of the uses of polymers?
new packaging materials, waterproof coatings for fabrics, dental polymers, smart materials, hydrogels
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Why is waste disposal a problem for polymers?
Not biodegradable, so they are not broken down by microbes
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How are plastic bags made?
From polymers and cornstarch so they breakdown more easily
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How is ethanol produced?
By hydration of ethene with steam in the presence of a catalyst or via Fermentation with yeast, using renewable resources. Sugar -> Carbon Dioxide + Ethanol
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How is oil extracted in plants?
The plant material is crushed and the oil is removed by pressing or in some cases by distillation. Water and other impurities are removed.
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Why are vegetable oils important fuel and foods?
They provide a lot of energy and with nutrients
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Why are vegetable oils useful in cooking?
Have higher boiling points than water so can be used to cook foods at a higher temperatures than by boiling. This produces quicker cooking and different flavours but increases the energy that the food releases when it's eaten
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What do unsaturated oils contain?
C=C double bond so are unsaturated.
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How can unsaturated vegetable oils be hardened?
Reacting them with hydrogen in the presence of a nickle catalyst at about 60^0C (hydrogenating)
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Properties of hydrogenated oils
Higher melting and boiling points. Wha(useful as spreads and in cakes and pastries)
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What is an emulsion?
Made up of lots of droplets of one liquid suspended in another liquid.
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Is an emulsion thicker or thinner than either oil or water?
Thicker
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What does hydrophobic mean?
Attracted to the oil (doesn't like the water - the tail)
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What does hydrophilic mean?
Attracted to the water (the head)
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What does the earth consist of?
Core, mantle, crust and surrounded by the atmosphere
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What causes the tectonic plates to move?
Convection currents within the Earth's mantle driven by heat released by natural radioactive processes cause the plates to move at relative speeds of a few cm per year
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What are the proportions of different gasses in the earths atmosphere?
80% Nitrogen and 20% Oxygen and a small proportion of various other gases
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Describe 1 theory of how life was formed
Involves the interaction between hydrocarbons, ammonia and lightning
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What has produced the oxygen that is now in the atmosphere?
Plants and algae
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What happened to all of the CO2 from in the atmosphere?
It gradually got locked up in sedimentary rocks as carbonates and fossil fuels
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What is air?
Is a mixture of gases with different boiling points and can be fractionally distilled to provide a source of raw materials used in a variety of industrial processes
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Card 2

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What are electrons?

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Move around the nucleus. They're negatively charged

Card 3

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What are the charges of protons, neutrons and electrons?

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Card 4

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Why do atoms have no overall charged?

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Card 5

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What do elements constist of?

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