Chemistry Unit 1

Chemistry Unit 1

1. Neutrons- Mass of 1. Charge of 0.

   • Protons- Mass of 1. Charge of +1
     • Electrons- Mass of almost 0. Charge of -1
       • Ionic bonding- An ionic bond takes place between a metal and a non-metal. If an atom loses 1 electron, it will have a charge of +1. If it loses 2 electrons, it will have a charge of +2 because electrons are negatively charged
         • The products in a reaction always = the reactants
           • No atoms are made or destroyed in a reaction, they are just bonded differently
             • This is called the conservation of mass
               • Titanium is used for artificial hips and bones and for oil rigs at sea. It has a low density, is strong and resists corrosion.
                 • Structure of the Earth- Volcanoes and earthquakes usually happen together. This is because they are the result of movement below us and the build up of pressure.
                   • Inner core, outer core, mantle and crust
                     • Convection currents in the mantle. Radioactive core produces heat. Tectonic plates in the crust
                     • Tectonic plates move because the radioactive core produces heat which causes convection currents in the mantle. These currents then cause the tectonic plates to move. This can cause earthquakes.
                       • Evidence for plate tectonics- Continents fit like jigsaw pieces. Fossils. Volcaones and mountains in straight lines. Rock minerall content is the same in each continent.
         • Soot(carbon) particles- Global dimming. Incomplete combustion of hydro-carbons release soot into the atmosphere which blocks out sunlight. This reduces the amount of sunlight that reaches the earth's atmosphere. This could prevent the growth of crops.
           • Sulphur- Acid rain. Often, hydrocarbons stay sulphur atoms. These react with oxygen when a fuel is burnt to produce sulphur dioxide. Sulphur dioxide reacts with water to form sulphuric acid which damages trees&buildings.
             • Carbon dioxide- global warming. Carbon reacts with oxygen to produce carbon dioxide. This absorbs the infrared radiation from the sun and traps the heat energy in tjhe atmosphere. This could increase the global temperature and therefore inhibit the growth of crops and change the climate.
             • Nitrogen- Acid rain. (Nitrogen oxides). Hydrocarbons stay nitrogen atoms very often. These react with oxygen when a fuel is burned to produce nitrogen oxide. This reacts with water and forms nitric acid and damages trees&buildings.
     • Copper is used in wires, pipes and tanks. It is a good conductor and is hard and strong. It can be bent and doesn't react with water.
       • Aluminium is used in aeroplanes, power cables, cooking foil and drink cans. It is strong, has a low density, can be bent and is corrosion resistant.

2. Protons and neutrons in core of atom. Electrons spread around the outer shell of the atom and orbit the nucleus in electron shells.

   • Metals are on the left hand side of the periodic table. Non-metals are on the right.
     • Number of group= Number of outer electrons
       • Group 1= Alkali metals. They react with water to form a metal hydroxide(An alkali) and a hydrogen gas. E.g. Lithium + water-> lithium hydroxide + hydrogen
         • Alkali metals each have one electron in their outer shell so are found in group 1.
           • Atoms react to gain full outer shells Some lose and some gain electrons. Atoms with a full outer shell don't react because they are stable atoms who don't need to gain or lose any electrons to achieve a full outer shell
             • Sodium (2,8,1) is less reactive than potassium (2,8,8,1) because in potassium, the outer electron is further away from the positive charge in the nucleus and can therefore get lost easier
               • Phytomining- Involves plants to extract copper. The plants are deliberately planted on low grade ore sites. The plants take up copper compounds in the roots. The plants are then burned. The ash is rich in copper which can then be extracted. Extraction is usually done by displacement, using scrap iron. This method can also be used to remove metal ions which are contaminating the land.
                 • Advantages of recycling metals such as copper- Saves 85% of energy used to extract from its ore. Conserves natural resources. Cheaper. Cuts down on landfill.
                   • Recycling plants is cheaper than extracting.
                   • Particulates may cause global dimming. In the atmosphere, particulates reflect sunlight back into space- as more particulates enter the atmosphere, less sunlight reaches the Earth's surface.
               • We get oil from food through distillation, crushing or pressing. Nuts, seeds and fruits contain oils.
                 • To produce sunflower oil, we crushed nuts with pestle and mortar. We then added water and pressed it onto paper. It formed a paste.
                   • To produce a sample of limonene, we put water in a conical flask and heated it with a bunsen burner. We used a measuring cylinder to collect the oil and used bromine to check if it was an oil.
             • An ore = A metal that can be extracted from rock (and other elements)
               • + of extracting metals from their ore- Provides jobs. Useful products made. Money to areas. Services (e.g. public transport) improved
                 • - of extracting metals from their ore- Noisy. Damages landscape. Loss of habitats. Deep mines are dangerous. Uses a lot of energy.
                   • An alloy is a metal mixed with another element, either metal or non-metal
                     • Sulfur dioxide, carbon dioxide and nitrogen dioxide all cause acid rain.
                       • Acid rain makes lakes more acidic. Some species of water animals and plants cannot survive if the water is too acidic. Acid rain also damages trees. It dissolves soil nutrients and washes them away before the tree roots can take them in. It also damages the waxy leaves coatings. The leaves can then no longer produce food for the trees
                         • 2 ways of reducing acid rain- Remove sulfur impurities from fuels like diesel. Some powerstations remove sulfur dioxide from gases by adding limestone powder.
                 • Stainless steel is made with chromium and nickel. It is corrosion resistant.
             • Saturated fat- single bonds between carbon atoms. Unsaturated fat- Double bonds. Saturated fats are unhealthier because they are made of animal fats whilst unsaturated fat is made of plant oils.
               • Polyunsaturated- Many double bonds. The oils are made from long chain hydrocarbons.
                 • Test for unsaturated fat- Bromine water goes from orange to colourless (clear). It decolourises.
           • Atom- Smallest particle. made up of P,N&E. Element- Made of 1 type of atom. Compound- 2 or more elements chemically joined together E.g. Sodium= an element but Sodium Chloride = a compound.
             • Alloys- Gold + copper= makes gold cheaper and harder. Aluminium + copper= Makes aluminium harder. Copper + zinc= Makes brass harder. Iron + chromium + nickel = stainless steel: stronger.
               • Impure iron (96%) is brittle. It's impure because it contains carbon. Carbon is used to reduce iron oxide to iron.
                 • Alloys of iron: Low carbon steel (0.5% carbon) = soft and easily shaped because most carbon is removed. High carbon steel (2.5% carbon) is hard because a bit of carbon is removed.
                   • Over millions of years, green plants evolved in the oceans. They removed the co2 from the air and gave off oxygen (photosynthesis). The carbon dioxide levels dropped and oxygen levels rose. Lots of carbon was 'locked up' in rocks and fossil fuels. As oxygen levels rose, animals evolved. In the past 200 years, co2 levels have risen again because of fossil fuels being burnt
           • An ion is something that has gained or lost electrons
             • Cathode= -VE Anode = +VE
               • Electrolytes conduct the electricity as they contain ions which are free to move. Electrons are taken away at the anode and given away at the cathode. Copper is extracted at its ore by reduction with carbon but electrolysis is also needed to 1) purify it and 2) so copper is a good conductor
                 • Conditions needed to make a polymer: Temperature, high pressure and a catalyst
                   • Addition polymerisation- Process to make polymers. Plastics with different properties can be made by changing the temperature, pressure and other elements.
                     • Polymer examples- Plastic bags, rope, cups, PVA glue, Duck tape, non-stick pans.
             • Polymers are not biodegradable, meaning that they will not be broken down by micro-organisms. However, new plastics have been developed which are biodegradable as they use corn starch.
             • Biodegradable- A material that can be broken down by micro-organisms.
               • + Plastic bags are cheaper to transport, produce and recycle than paper bags. They are durable, low cost and strong. They are reusable. They are recyclable BUT very few are recycled. - They aren't biodegradable. They are made from non-renewable energy sources (oil-based chemicals). They can block drains and harm wildlife when not disposed of properly. They can suffocate children, too.
   • Limestone is made in a kiln with clay to make cement. Cement can be mixed with water and sand to make mortar. Concrete is made by mixing cement with sand, water and aggregate (gravel)
     • In order to remove a metal using reduction, it must be less reactive than carbon. If it is more reactive than carbon, then electrolysis is required.
       • Uses of electrolysis- purifying copper, plating metals with silver and gold, extracting metals (such as aluminium) making chlorine, hydrogen and sodium hydroxide
         • Electrolysis is the splitting up of compounds using electricity
     • Polymer diagram- Put a bracket around the diagram and add an n in the corner. Write out the equation at the bottom, too.

3. IONIC BONDS ONLY EXIST IN COMPOUNDS OF METALS AND NON-METALS

4. All carbonates react with acids. The products are salt, water and carbon dioxide. The name of the salt depends on the metal and carbonate used. Hydrochloric= Chloride, Sulphuric= Sulphate and Nitric=Nitrate

   • Exothermic- Water heats up (heat given out) Endothermic- Water cools down(Heat taken in from surroundings)
     • Test for carbon dioxide- Limewater goes cloudy
     • Limestone= Calcium carbonate= CaCo3
       • Calcium carbonate decomposes with heat to give calcium oxide
         • Advantages of limestone- Attractive,durable and stong. Versatile. Good building material. Found in countryside quarries: Provides jobs. Contributes to economy as it is exported. It's quite cheap
           • Disadvantages- Can be damaged by chemical reactons in acid rain. Affects wildlife. could damage tourist industry and land. Transporting it creates extra traffic. Takes up farming space
             • Calcium carbonate (CaCo3)-> Calcium oxide (CaO)-> Calcium hydroxide Ca(OH)2
             • A metal carbonate carbonate contains a metal, carbon and oxygen
               • Decomposition reaction- A metal carbonate breaks down when heated and produces a metal oxide and carbon dioxide. This carbon dioxide is tested via the limewater test- It goes cloudy when CO2 is present
         • Alkanes- Cn H2n+2 Alkenes- CnH2n
           • It is found in the Earth's rocks. When animals died, they were buried by mud which then turned into rock as temperature and pressure increased. The remains were 'cooked' and eventually turned into crude oil
             • CH4 + 2O2 -> CO2 + H2O (Burning of hydrocarbons)
             • Burning fossil fuels doesn't cost a lot and they are plentiful so go a long way. They can be extracted quickly because of advancing technology. There are means of controlling the pollution from these products. Fossil fuels generate money for countries from the purchase of fuels. But they are a non-renewable energy source so will run out soon. So they will become more expensive to extract as supply becomes limited. Also, their pollution leads to acid rain, global warming and oil spillages.
               • Hydrogen is an equally good material. it is made by reacting steam with coal or natural gas, so it is environmentally friendly. Only water is prouduced so it doesn't contribute to polluting the environment. But, it is difficult to make/handle hydrogen and it is highly dangerous and flammable.
         • An emulsion is when two chemicals which would not normally mix together, mix together. A mixture is two or more chemicals which don't share bonds.
           • Emulsifiers allow oil and water to mix. The hydrophillic head attaches to the water, the hydrophobic tail attaches to the oil and keep it suspended to mix the two.
   • Alkenes are unsaturated hydrocarbons with double bonds. They are formed by heating up alkanes.
     • The problem with fractional distillation is that a lot of long chain hydrocarbons don't burn. To change the size if these, cracking is performed. This is done by heating paraffin and wool in a test tube with porcelain chips to produce a gas. This is done to produce shorter hydrocarbon chains. Unsaturated hydrocarbons mean there are double bonds. The product from cracking makes the bromine water go clear. If this occurs, it's because double bonds are present. This is the test for unsaturated hydrocarbons. Cracking involves jheating long chain hydrocarbons over a catalyst.

5. Earthquakes- Occur when tectonic plates move suddenly against eachother. They are very common at plate boundaries. Undersea earthquakes could cause huge tsunamis.

   • Scientists can tell if there will be an earthquake if there are earthquakes nearby, if the volcano shape changes, if the volcano gives off more gases than normal.
   • The bonds in alcohol are easily broken and it is extremely flammable.
     • The hydration of ethene occurs when Ethene gas is reacting with steam in the presence of a phosphoric acid catalyst to produce Ethanol. It requires a lot of energy and a large amount of pressure&high temperature. It uses non-renewable energy. However, the ethanol prduced is very pure and the process is quick and continuous.
       • The fermentation of sugar with yeast is where yeast converts glucose into Ethanol by anaerobic reaction. Although it uses very little energy and a renewable energy source, the process is very slow and the ethanol produced is not very pure.
         • I would say that although the hydration of ethene happens very quickly and produces a large amount of ethene, it uses a non-renewable energy source and a lot of pressure. So fossil fuels are used. So it is bad for the environment, therefore the fermentation method is better.

6. The earth's atmosphere has changed a lot since it was first formed. When the earth was first formed, it was much hotter than it is now and the atmosphere was made up mainly of carbon dioxide and ammonia (NH3)

   • The tectonic plates moved a lot and volcanoes erupted. This released huge amounts of water vapour into the air. Over millions of years, the earth cooled and so did the water vapour. This water vapour condensed and fell as rain. This formed the world's rivers and oceans.

7. Ionic bond : metal & non-metal.. Covalent bond : Non-metal and non-metal. Metallic bond: metal& metal

   • Element- A material made from one type of atom. A compound- A material made from two or more types of atom that are chemically joined together. Mixture- A combination of elements and compounds that are not chemically joined together and can be separated.
     • Hydrocarbon- A material made from hydrogen and carbon. Crude oil- A mixture of hydro-carbon compounds.
       • Crude oil- A mixture of hydrocarbons. It can be separated because it is a mixture of compounds and there are no chemical bonds. It is separated to make useful products, such as fuels, using fractional distillation
         • Alkanes are saturated hydrocarbons. This means their carbon atoms are joined together by a single bond and are unreactive except when they react with oxygen (through burning or combustion)
           • Biofuels are better economically compared to fossil fuels. Greenhouse gas production is lower than fossil fuels and fuel prices are lower because more is produced. But, crops used for biofuel could have been used to feed people. Also, modified engines are required as well as more people, increasing the cost.
             • Biofuels are the best to use because although hydrogen is environmentally friendly, it is extremely dangerous. Also, biofuels are more sustainable and lower prices for people who use it.

8. Momomer: A very small, unreactive alkene molecule.

   • Under high pressure and in the presence of a catalyst, double bonds open up. They can link up to form a polymer. This is known as polymerisation.
   • A polymer is simply more than one monomer joined together.