Chemistry paper 2

• Group 1 - Alkali metals


  Reactivity increases as you go down the group

  As you go down there are more shells

  The electron on the outer shell is further away from nucleus- less attraction between negatively charged electron and positive protons in the nucleus

  Easier to lose electron
• Alkali metals


  Soft

  Low boiling points
• Group 7 - Halogens


  Reactivity decreases as you go down the group

  As you go down there are more shells meaning less attraction so it is harder to gain the electron
• Group 0 - Noble gases


  Unreactive - inhert as they have a full outer shell

  Boiling point and density increases as you go down the group

  non-flammable
• Crude oil in and...


  Gases- used for cooking and heating homes

  Petrol- used for cars

  Kerosene- used for aircrafts

  Diesel oil- used for cars and trains

  Fuel oil- used for ships and power stations

  Bitumen- surfacing roads and roofs
• Homologous series 


  Compounds which:

  Have the same general formula

  Show a gradual variation in physical properties

  Have similar chemical properties

  Differ by $CH_2$
• Types of alkanes - MEPB


  M- methane ( one C atom )

  E- ethane ( two C atoms )

  P- propane ( three C atoms )

  B- butane ( four C atoms )
• What is cracking?


  Long chains of alkanes are not as useful as short chain alkanes. To solve this supply issue we can use cracking to turn it into a short chain alkane and short chain alkane.
• Impurities in fuels


  • mainly hydrocarbons but may contain impurities such as sulfur
  • when burned they give of sulfur dioxide
  • this then dissolves in water to form sulfuric acid and falls as acid rain
• Problems with acid rain


  • can damage statues
  • can kill fish in ponds
  • can kill plants as it is taken up from the soil
• Early atmosphere- scientists believe the early atmosphere came from volcanic activity. Volcanos release large amounts of carbon dioxide and water vapour


  the early atmosphere probably contained:

  • little to no oxygen
  • water vapour
  • small amounts of other gases such as methane, ammonia
• Change in the atmosphere


  Water vapour- decreased as the planet cooled as the water vapour condensed and formed oceans

  Oxygen- increased as algae and plants formed- carrying out photosynthesis- reducing carbon dioxide and increasing oxygen

  Carbon dioxide- decreased as carbon dioxide dissolved in the oceans that formed. Also due to plants photosynthesising
• Oxygen gas test


  Use a glowing splint and place it into the gas, if it is oxygen it will relight
• Greenhouse gases - carbon dioxide, water vapour, methane


  They absorb heat radiated from the Earth then releasing energy which keeps the Earth warm. This is the greenhouse effect.
• Test for chlorine


  Use damp blue litmus paper, if chlorine is present It will be bleached white
• What are catalysts used for?


  increase the rate of reaction without being changed or used up
• What is crude oil?


  Mixture of substances called hydrocarbons
• What does exothermic mean?


  Energy is transferred from stores of energy in chemical bonds to the surroundings - heat exits, strong bonds formed and energy released
• What does endothermic mean?


  Energy is transferred from the surroundings to stores of energy in chemical bonds, heat enters, bonds are broken and energy supplied
• What does the rate of reaction depend on?


  Temperature, catalyst, concentration ( for pressure ) and surface area of a solid
• Flame tests 


  Barium (Ba) - Pale green

  Calcium (Ca) - Orange/red

  Copper (Cu) - Green/blue

  Lithium (Li) - Crimson red

  Sodium (Na) - Orange/yellow

  Potassium (K) - Lilac
• What is a polymer?


  Long chain of monomers
• Describe a metal


  strong electrostatic forces of attraction so it takes a large amount of energy to break apart these bonds meaning they have high melting points. They also have delocalised electrons which means they are goof conductors of electricity.
• Describe composite materials


  A mixture of two or more materials combined to produce a material with improved properties

  Examples: laminates, reinforcement and matrix
• What are the risks of nanoparticles 


  • small size
  • can be breathed in or pass through cell surface membranes
  • could catalyse harmful reactions or carry toxic substances stuck to them
  • risks hard to determine as they have not been in use for long
• What is the difference between an alkene and alkane


  Alkene- unsaturated as they don't have as many bonds as possible

  Alkane- full saturated with all their bonds
• What happens in the combustion of alkenes


  They burn but with a smokier, yellow flame compared to alkanes as there is incomplete combustion. Also release less energy per mole than alkanes sp they are not used as fuel
• Testing for alkanes/alkenes - halogens


  Alkane + bromine water ( no reaction )

  Alkene + bromine water ( turns colourless )
• Why would catalysts be used in industry?


  • products made faster
  • reactions occur at lower temperatures
  • do not need to be replaced - initial cost
  • makes the process more profitable
• What are the effects of carbon monoxide?


  It is a colourless, odorless toxic gas, it combines with haemoglobin irreversibly in red blood cells and this prevents oxygen combining. This reduces the amount of oxygen carried in the bloodstream.
• What is nanoscience


  the science of very small particles