Chemistry Unit 1 Part 1

Atoms and elements
1. Inside atoms
  1. Proton = +1
  2. Neutron = 0
  3. Electron = -1
  4. Mass number
  5. Atomic no. (number of protons and electrons)
  6. Group 1 elements only have 1 electron in their highest level
    1. Potassium and sodium
  7. Group 0 have full outer shells so they are very stable and unreactive
    1. Neon and argon
2. Inside compounds
  1. Made up of two or more elects , strongly joined together
  2. Ionic bonding
    1. Metal and non-metal
    2. Metal transfers one electron to the non metal
    3. Each atom has a full outer shell
    4. Charged atoms = ions
    5. Forces of attraction (negative and positive) are ionic bonds
  3. Covalent bonding
    1. Non-metal and non-metal
    2. Atoms share electrons to form covalent bonds
3. An atom is the smallest particles of a chemical elects that can exist
4. An element is made of just one sort of atom
5. All the elements are listed in the periodic table
  1. The vertical columns are called groups
    1. The elements in a group have similar properties
  2. Group 1 are silvered-coloured metals that react with water
  3. Elements in group 0 are gases at room temperature and don't usually react with other substances
  4. Elements on the left of the stepped line are metals and on the right are non-metal
Chemical reactions
1. Chemical equations
Limestone
1. The lime cycle
  1. Calcium carbonate (limestone)
    1. Heat
      1. Carbon dioxide gas
      2. Calcium oxide
        Add a few drops of water
        Solid calcium hydroxide
        Add more water and filter
        Calcium hydroxide solution (limewater)
        Add carbon dioxide
2. Products from limestone
  1. Crushed into small lumps to make aggregate
  2. Calcium oxide and calcium hydroxide both form alkaline solutions with water
    1. Neutralise acidity in lakes/oils and acidic waste gases produces by burning coal in power stations
  3. Cement
    1. Crush limestone rock into small pieces
      1. Add powdered clay and heat the mixture to 1450 degrees in a rotating kiln
        Thermal decomposition ( calcium oxide (quicklime) and carbon dioxide)
        Add a little calcium sulfate powder
  4. Concrete
    1. Mix sand , cement , aggregate and water
  5. Mortar
    1. Mixing a thick paste from cement , sand and water
  6. Decomposing metal carbonates
    1. Pattern
      1. Metals low in the reactivity series = small amounts of energy to break them down
        High reactive metals = lots of energy to decompose them
        Very reactive metals = don't decompose at bunsen burner temperatures
        Potassium carbonate
        Sodium carbonate
        Copper carbonate
    2. copper carbonate (green) --> copper oxide (black) + carbon dioxide
3. Quarries
  1. Benefits
    1. Provides jobs where they may be scarce
      1. Quarries produce materials worth billions and this contributes to the countries economy
  2. Problems
    1. In attractive areas it can damage tourism
      1. Transportation creates traffic
        It takes up land space which is then unavailable for farming and recreation
4. Formed from the shells of creates that lived in shallow seas
5. Raw material for the production of materials including cement , mortar and glass
6. Attractive , durable and strong
7. Cut into blocks
8. The surface of limestone can be damaged by acid rain
  1. calcium carbonate + sulphuric acid --> calcium sulfate + carbon dioxide + water
Magnificent metals
1. Stunning steel
  1. Iron
    1. Cast
      1. Re-melting blast furnace iron and adding scrap stewl makes cast iron
      2. Has a high stretch in compression - used for cannons and cooking pots
    2. Pure
      1. Remove impurities
      2. Regular arrangement of atoms so they slide over each other making it soft and easy to bend into shapes
  2. Carbon steels
    1. Low % of carbon - less than 0.3%
      1. Easy to make into shapes
      2. Car body panels and food cans
    2. High % of carbon - 0.6 - 1 %
      1. Hard and strong
  3. Stainless steel
    1. Iron and steel rust when they react with water or oxygen in the air = corrosion
      1. Weakens structures - cost money and lives
    2. Stainless steel doesn't rust - corrosion resistant
    3. Contains chromium atoms
    4. Cutlery , surgical instruments and kitchen sinks
  4. Mainly iron mixed with certain amounts of carbon
  5. Alloy (mixture of a metal with one or more elements ) - layers of atoms so it can't slide easily
2. Copper
  1. Phytomining
    1. Plant certain plants on low-grade copper ores
      1. Plants absorb the copper compounds
        Burning the plants produces ash that is rich in copper compounds
  2. Bioleaching
    1. Some bacteria can obtain their nutrients and energy from copper compounds in copper ores
      1. The bacteria produce solutions of copper compounds
        Chemical reactions or electrolyse extract the copper
        Very slow process
  3. Uses
    1. Pipes as it bends easily
    2. Wires as it conducts electricity well
    3. Coins when mixed with nickel
    4. Bottom of plans as it conducts heat well
  4. Obtaining pure copper
    1. 1. Dig ore from an open cast mine
      1. 2. Concentrate the ore to separate copper minerals from the waste rock of the ore
        3. Make a solution of copper compounds from the ore and use electrolysis
        3.Heat the concentrated ore in a furnace where chemical reactions remove other elements (smelting)
        4. Electrolysis
        Negative electrode is made of pure copper
        Impure copper forms the positive electrode
        During electrolysis , positive copper ions move to the negative electrode
        Waste material falls to the bottom of the beaker and it damages the environment
  5. Can also be obtained from solutions of copper salts by adding scrap iron to the solutions
    1. iron + copper sulfate --> iron sulfate + copper
3. Titanium and aluminium
  1. Titanium is extracted using a multi-step process which uses lots of energy so is expensive
    1. Low density
    2. Resists corrosion
    3. Transition metal
    4. Aeroplanes , artificial hips and bone pins or oil rigs at sea
  2. Aluminium is extracted by electrolysis , which uses a lot of electrical energy which is expensive
    1. Low density
    2. Corrosion resistant
    3. Aeroplanes , overhead power cables , drink cans and cooking foil
  3. Expensive because they can't be extracted easily by heating their ores with carbon
    1. Aluminium is above carbon in the reactivity series , its atoms are joined very strongly to oxygen atoms in bauxite
      1. If you heat titanium oxide with carbon you make it titanium carbide and this is a brittle metal
  4. Recycling - creating new cans only uses 10% of the energy and less pollution is created
4. Transition metals
  1. Central block of the periodic table
  2. Shiny surface weh freshly cut
  3. Can be bent or hammered without cracking
  4. Good conductors of heat and electricity
5. Iron
  1. Extracting ores
    1. 1. Put the iron ore in a hot blast furnace with coke (carbon)
      1. 2. Oxygen is removed from the iron oxide in reduction reactions. The products are iron and carbon dioxide
    2. If below carbon they are also extracted by heating their oxides with carbon
  2. Too reactive to exist on its own
    1. Joined to other elements in naturally occurring compounds called minerals (mixed with sand or rock) = ORES
6. Gold
  1. Found as a metal on its own as it is unreactive
    1. Hardly ever joins to other elements to form compounds
  2. In its NATIVE STATE
Making crude oil useful
1. Looking into oil
  1. Alkanes
    1. Longer chain alkanes are more viscous because their molecules get more tangled (don't pour easily)
      1. The smaller the molecules , the lower the boiling point
        Alkanes with small molecules catch fire more easily
2. Burning dilemmas
  1. Carbon dioxide
    1. Formed by the complete combustion of hydrocarbons
    2. Global warming
      1. Impacts
        Climate change
        Weather patterns change
        Extreme weather events
        Some species will die
        Some species such as the mosquito may spread over wider areas
        Melting ice caps
        Sea levels rise
        Increased flooding
      2. 1. Radiation from the Sun enters the Earths atmosphere and reaches the Earth surface
        2. The radiation warms up the Earths surface
        3. The Earths surface radiates heat energy, Some of the heat energy goes directly into space whilst some is absorbed by carbon dioxide gas in the atmosphere
        4. The atmosphere radiates some of its heat energy back towards the Earth and the Earths surface gets hotter
      3. Solutions
        Use less or alternate fuels
  2. Particulates
    1. Burning diesel produces tiny pieces of solid
    2. Causes global dimming
      1. In the atmosphere , particulates reflect sunlight back into space - so less reaches the earths surface
  3. Acid rain
    1. When coal burns it produces sulfur dioxide gas , carbon dioxide and water
    2. If sulfur dioxide goes into the air it dissolves in water in clouds and makes acid rain
    3. Oxides of nitrogen such as nitrogen dioxide , are formed when hydrocarbon fuels burn at high temperatures in car engine
    4. Makes lakes more acidic
      1. Damages trees (dissolves soil nutrients and washes them away , also damages the protective waxy coating of leaves - can no longer produce food)
        Damages limestone buildings
  4. Carbon monoxide
    1. Poisonous
    2. Incomplete combustion
3. Separating oil fraction
  1. 1. Crude oil is evaporated at 450 degrees and enters the fractional column as a gas
    1. 2. The fractional column has a temperature gradient ( it is hotter at the bottom and cooler at the top)
      1. 3. Once a fraction has cooled to below its boiling point (turns from a gas into a liquid) it is removed
        4. Fractions with higher boiling points are removed at the bottom of the column and vide versa
4. Contains many hydrocarbons (compounds of hydrogen and carbon)
5. Mixture , so it is not chemically joined and each hydrocarbon has its own properties
Biofuels
1. Plant oil fuels are renewable but they produce carbon dioxide on burning
2. Problems
  1. Deforestation to make room for crops damages biodiversity
    1. Emissions of oxides of nitrogen cause asthma and lung disease
      1. Produces lots carbon dioxide
        Evicted people from land
        Land could be used to grow food
3. Benefits
  1. Provides jobs
    1. Generate renewable sources for electricity
      1. Carbon neutral

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Chemistry Unit 1 Part 1

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