Chemistry Paper 1

• Compound


  Two or more elements chemically combined together
• Mixture


  Contains two or more elements not chemically combined together
• Methods to separate mixtures


  • Crystallisation
  • Filtration
  • Chromatography
  • Simple Distillation
  • Fractional Distillation
• Crystallisation


  1. Heating a solution so that the solution evaporates (the water) leaving the solute in the evaporating dish

  2. Heat it and then leave the solution to cool so that the crystals are left in the dish
• Filtration


  1. Use filter paper and a funnel to separate the solution containing the solid and liquid

  2. Through the funnel, the solid will be left in the funnel paper and the liquid only filtrate will be in the beaker under the funnel

  3. You then have your crystals from your original solution
• Chromatography


  1. Start by drawing a baseline on the chromatography paper using a pencil

  2. Place a small spot of the sample mixture on the baseline

  3. Pour the solvent into a beaker

  4. Place a glass rod over the beaker, and tape or clip the paper to it, ensuring that the paper's base just touches the solvent without being submerged

  5. Allow the solvent to slowly travel upwards through the paper, taking with it a few soluble pigments from the sample mixture

  6. Remove the paper from the beaker before the solvent reaches the top

  7. Analyse the chromatogram to identify the different components of the sample mixture

  8. Mark the distance travelled by the solvent
• History of the Atom

  • Dalton "Billiard Ball" - John Dalton, 1803
  • Plum Pudding Model - JJ Thompson, 1897
  • Rutherford Model - Ernest Rutherford, 1909-1911
  • Bohr Model - Niels Bohr, 1913
  • Current Nuclear Model - James Chadwick, 1932
• Proton


  Positive with a mass of 1
• Neutron


  Neutral (no overall charge) and has a mass of 1
• Electron


  Negative and has a very small mass
• Differences between Metals and Non-Metals

  • Metals have 1-3 outer shell electrons, metallic bonding, good conductors of electricity, basic oxides, many react with acids, shiny, solid at room temp, malleable
  • Non-metals have 4-7 outer shell electrons, covalent bonds, poor conductors of electricity, acidic oxides, don't react with acids, dull, non reflective, brittle, low melting and boiling points
• Periodic Table


  • Rows are called periods and columns are called groups
  • The column or Group that an element is in determines the amount of electrons that are in its outer shell
• Group 1 - Alkali Metals


  • They have a single electron in their outer shell
  • As you go down the group the reactivity of the group increases
• Group 0 - Noble Gases

  • They are unreactive and do not easily form molecules because their atoms have stable arrangements of electrons
  • They have eight electrons in their outer shell, except for helium, which has only two electrons
  • The boiling points of the noble gases increase with increasing relative atomic mass (going down the group)
• Group 7 - Halogens


  • They have similar reactions because they all have seven electrons in their outer shell
  • The halogens are non-metals and consist of molecules made of pairs of atoms
  • As you go down the group the relative molecular mass, melting point and boiling point increases but the reactivity of the elements decreases going down the group
• Transition Metals


  • Higher melting points
  • Higher densities
  • Greater strength
  • Greater hardness
• Reactions of Group 1 elements with oxygen


  They react quickly with oxygen in the air at room temperature
• 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 yet to be discovered
• Compound


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

  • Electrons on the shells around the outside
  • Protons in the middle
  • Neutrons in the middle
• Nucleus


  The part in the middle of an atom containing protons and neutrons
• Protons


  Have a mass of 1 and a charge of plus 1
• Neutrons


  Have a mass of 1 and a charge of zero
• Electrons


  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 in an atom
• Balancing a chemical equation

  1. Write the reactants and products

  2. Count the number of each element

  3. Adjust the coefficients to balance the equation
• Important 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 for mixtures

  • Distillation
  • Evaporation
  • Filtration
  • Fractional distillation
• The plum pudding model was the previous model of the atom before Rutherford and Marsden's experiment
• Rutherford and Marsden's experiment led to the development of the nuclear model of the atom by Bohr
• Rutherford discovered the nucleus, Chadwick discovered neutrons, and Bohr developed the current model of the atom
• Groups in the periodic table

  Indicate the number of electrons in the outer shell of an element
• Periods in the periodic table

  Indicate the number of electron shells in an element