Chemistry Paper 1

• The periodic table is a list of all the elements which are known to exist
• Element


  A single type of atom
• Atom


  A very small thing, the word atom is Greek for 'uncuttable'
• The periodic table tells us loads of information about the elements
• There are still loads of elements yet to be discovered
• Compound


  Two or more elements that are chemically bonded together
• Structure of an atom

  • Electrons
  • Protons
  • Neutrons
• Protons


  In the nucleus, have a mass of 1 and a charge of plus 1
• Neutrons


  In the nucleus, have a mass of 1 and a charge of zero
• Electrons


  In the outer shells, have a mass of 1/2000 and a charge of minus 1
• Atomic number


  The number of protons and electrons in an atom
• Mass number


  The number of protons plus the number of neutrons
• The atomic number tells us the number of protons and the number of electrons in an atom
• The mass number is the number of protons plus the number of neutrons
• Balancing a chemical equation

  1. List the reactants and products

  2. Count the number of each element

  3. Adjust the coefficients to balance the equation
• Chemical formulas to learn

  • Carbon dioxide (CO2)
  • Water (H2O)
  • Oxygen gas (O2)
  • Hydrogen gas (H2)
  • Nitrogen gas (N2)
  • Ammonia (NH3)
  • Hydrochloric acid (HCl)
  • Sulfuric acid (H2SO4)
• Element


  A pure substance made of a single type of atom
• Compound


  Two or more different elements chemically bonded together
• Mixture


  Lots of different things, some chemically bonded, some not
• Separation techniques


  • Distillation
  • Evaporation
  • Filtration
  • Fractional distillation
• The plum pudding model of the atom was replaced by the nuclear model proposed by Rutherford and Marsden
• Rutherford discovered the nucleus and protons, Chadwick discovered neutrons, and Bohr developed the current atomic model
• Groups


  Go down the periodic table, indicate the number of electrons in the outer shell
• Periods


  Go across the periodic table, indicate the number of electron shells
• Determining electronic configuration


  1. Identify the group and period

  2. Draw the electron shells

  3. Fill the electrons in the shells
• Metals lose electrons and form positive ions, nonmetals gain electrons and form negative ions
• Groups on the periodic table

  • Group 1 (alkali metals)
  • Group 2 (alkaline earth metals)
  • Group 7 (halogens)
  • Group 8 (noble gases)
  • Transition metals
• Newlands' early periodic table had flaws, Mendeleev's periodic table with gaps allowed him to predict undiscovered elements
• Noble gases


  Have a full outer shell and are unreactive
• Halogens


  Highly reactive nonmetals that form diatomic molecules and want to gain 1 electron
• A more reactive element


  Can displace a less reactive element in a compound
• Halogens are used as sterilizing agents, e.g. chlorine in swimming pools
• Alkali metals react violently with water, producing colourful flames used in fireworks
• Bromine cannot displace chlorine out of sodium chloride because chlorine is higher than bromine on the periodic table, so it's more reactive
• Displacement reactions


  Reactions where one element displaces another element from a compound, forming a new compound
• Halogens are mostly used for sterilizing things
• Halogens


  Want to gain 1 electron, the most reactive ones are at the top of the periodic table where there is least shielding between the electron they want to gain and the nucleus
• Alkali metals


  React very violently with water, producing flames and different colors which are used in fireworks
• Alkali metals are soft, grey metals which are easily cuttable and need to be kept in oil to prevent reaction with oxygen or water
• Reaction of metal with oxygen

  1. Metal plus oxygen forms metal oxide

  2. Metal oxide causes the shiny metal to dull