Chemistry paper 1

• compounds


  two or more

  elements chemically combined

  only separated by chemical reactions or electrolysis
• Mixtures 


  two or more elements or compounds which are not chemically bonded (separated by physical processes)
• Crystallisation

  • obtains solids from a solution
  • gently warm mixture, water evaporates, leaves salt crystals
• Simple distillation

  • obtains solvent from solution
• Atoms:

  1. Plum Pudding model-Thomson
  2. Alpha scattering experiment - Geiger and Marsden
  3. Nucleus - Rutherford
  4. Electrons - Bohr
• Atoms


  Protons = 1 (mass) = +1( charge)

  neutrons = 1 (mass) = 0(charge)

  electrons = very small (mass) = -1(charge)
• Atomic number 


  Number of protons
• Mass number


  Sum of protons and neutrons
• Number of neutrons = mass number - atomic number
• Isotopes 


  • Same number of protons DIFFERENT number of neutrons
  • same atomic number
  • DIFFERENT mass number
• Ions 


  • Atoms gain or lose electrons to become ions
  • metal atoms lose electrons (Positive)
  • non-metal atoms gain electrons ( negative)
• Group 0:


  • noble gases
  • full outer shell
  • Stable so not reactive
  • non-metals
• Group 1:

  • alkali metals
  • one outer shell electron
  • more reactive down group
  • low melting & boling point down group
  • easy to lose electrons futher from nucleus
  • alkali + water → metal hydroxide + hydrogen
  • low density
  • alkali metals + nonmetals = metal ion (+1)
• Group 7:


  • halogens
  • reactivity decreases down the group
  • harder to gain elections further from nucleus
  • halogen + metal= ionic salt
  • halide ion (-1)
  • more reactive halogen displaces less reactive one
• Ionic compounds:

  • atoms that Gain/ lose electrons=ion
  • Ionic bonds occur between positive and negative ions
  • metal atoms transfer electrons to to non-metals
  • strong electrostatic attraction
• ionic compounds 


  • giant structures of ions
  • high melting & boiling point
  • no electricity when solid
  • conducts electricity when molten
• Covalent compounds

  • Small molecules
  • Small number of non metal atoms
  • can’t conduct electricity
  • low melting and boiling points
  • weak intermolecular forces
• Diamond

  • giant, rigid covalent structure
  • all carbon atoms bonded
  • high melting pant
  • doesnt conduct electricity
• Graphite:

  • high melting point
  • 3 carbon atoms bonded
  • layered, hexagonal structure
  • weak intermolecular forces
  • layers slide so graphites soft and slippery
  • one delocalised electron from each carbon
  • conducts heat and electricity
  • nearly transparent
• Silicon dioxide:


  • lattice structure
  • each oxygen atom joined to two silicon atoms
  • each silicon atom joined to four oxygen atoms
• Fullerenes 


  • Different numbers of carbon atoms
  • hollow tubes / balls / cages
• Buckminister fullerene:

  • 60 carbon atoms
  • series of hexagons and pentagons
  • symmetrical so very stable
• Fullerenes used for :

  • delivering drogs in body
  • as catalysts
  • As lubricants
  • reinforcing materials
• polymers 


  • got big molecules
  • held together by strong covalent bonds
  • strong intermolecular forces
  • Solid at room temp
  • poly(ethene) = lots of ethene molecules in an addition polymersation
  • cheap and strong
• Metallic bonding 


  • Occurs in metallic elements and alloys
  • electrons in outer shell are delocalised
  • makes lattice held by electrostatic attraction
  • metallic bonding = positive ion + negative electron
• Properties


  1. Aluminium - ductile malleable, conductor, low density, corrosion resistant
  2. copper - ductile, malleable, conductor
  3. Gold - ductile, shiny, conductor
• Alloys 


  • Mixtures that contains a metal and other elements
  • Added elements disturb metal arrangement so layers don’t slide easily
• Mols

  • measure of number of particles in a substance
  • One mole of substance contains same number of particles (6.02 x 10^23)
  • mol=mass of substance / atomic OR formula mass