Chemistry paper 1

• john dalton suggested solid spheres and different types of them make up different elements
• jj thompson suggested plum pudding model as a ball fo positive charge w negative electrons stuck in it
• ernest rutherford fired alpha particles at a thin sheet of gold and found that the alpha particles would pass through the gold but some would bounce back
• niels bohr suggested electrons orbit the nucleus in shells
• james chadwick discovered the nucleus
• each group has similar chemical properties because they have similar numbers of electrons in their outer shells
• as you go down group 1, the reactivity decreases as the outer electron shells get further away from the nucleus

  = weaker forces of attraction
• group 1 are alkali metals
• group 1 are soft with low densities and boiling points
• group 7 are halogens and less reactive as you go down
• group 0 are noble gases, unreactive and non-flammable
• transition metals (centre) can form more than one ion
• transition metals are good catalysts and are coloured
• in group 7 when halogens gains an electron it becomes a halide
• ionic bonding: opposite forces attracted by electrostatic forces of attraction
• ionic compounds: high m and b point, conduct electricity when molten or dissolved in water
• ionic compounds: electrons are delocalised
• covalent bonding: sharing electrons
• simple molecular substances have strong covalent bonds bw atoms but weak intermolecular forces bw indivual ones
• simple molecular substances have low melting and boiling points to break bonds
• giant covalent substances don't conduct electricity, except from graphite
• diamond atoms are covalently bonded to 4 other carbon atoms
• graohite covalently bonded to 3 carbon atoms
• in graphite layers are hled together by weak covalent bonds, so can slip and slide over each other
• graphite has delocalised electrons so can conduct electricity and heat
• graphene can be arranged in tubes or spheres
• graphene can be used for nanotechnology or industrial catalysts
• in metallic bonding electrons are delocalsied and free to move
• if the mass increases randomly, one of reactants is a gas
• if the mass decreases randomly, one of the products is a gas
• wide range indicators are chemical dyes that change colour at different pHs
• pH probes and metres are more accurate bc no human judgement needed
• the relative mass of protons and neutrons is 1
• neutrons have no charge (0)
• isotopes are elements with the same number of protons but a different number of neutrons
• Neutralisation reaction RP

  1. Dilute acid in beaker + gently heat w. bunsen burner
  2. Add insoluble base, disappearing a bit at a time
  3. Some of base stops disappearing
  4. Base is 'in excess' and we have neutralised the base
  5. Filter excess copper oxide w a filter paper and funnel to leave copper chloride
  6. Heat in a water bath w. an electric heater to evaporate off some water
  7. Filter crystals again and leave to dry somewhere warm
• In metals, oxidation is gaining oxygen
• In metals, reduction is losing oxygen
• In electrons, oxidation is losing electrons
• In electrons, reduction is gaining electrons