Topic 1 - C1

• Isotope

  -> different forms of the same element

  -> same amount of protons and electrons (atomic number)

  -> different amount of neutrons (mass number - atomic)
• Compound

  -> substances formed from two or more elements

  -> chemically bonded
• Formula

  -> made up of elemental symbols to show the proportions of elements found in compound
• Mixtures

  -> made from either elements or compounds

  -> no chemical bonds
• Paper chromatography

  1. draw pencil (insoluble) line on bottom of filter paper
  2. add spot of ink to line and place sheet in beaker of solvent
  3. make sure the ink isn't touching solvent (otherwise might dissolve)
  4. solvent moves up paper carrying ink with it
  5. when solvent has nearly reached top of paper removed and let dry
• What are the two ways to seperate soluble solids from solutions?


  • evaporation

  • crystallisation
• Evaporation

  1. pour solution into evaporating dish
  2. slowly heat solution (bunsen burner or water bath)
  3. solvent will evaporate and solution more concentrated and crystals will form
  4. keep heating until left with dry crystals
• Crystallisation

  1. pour solution into evaporating dish and gently heat
  2. solvent will evaporate and solution more concentrated
  3. when some of solvent has evaporated or crystals start to form remove from heat and let cool
  4. salt should start to form crystals as it become insoluble in cold, highly concentrated solution
  5. filter crystals and leave to dry
• What is simple distillation used for?


  seperating out a liquid from a solution
• What is fractional distillation used for?


  seperating a mixture of liquids
• Simple distillation

  1. solution is heated so solution with lowest boiling point evaporates first
  2. vapour is then condensed and collected
  3. test of solution left in flask
• Fractional distillation

  1. put mixture into flask and put fractionating column on top, then heat
  2. liquid with lowest boiling point evaporates first and reaches top of column
  3. liquids with higher boiling point might start to evaporate but condenses towards top due to glass rods in column
  4. once lowest boiling point liquid is collected increase temperature to next lowest boiling point and repeat
• Order of atom discovery:

  1. solid spheres
  2. electrons and positive charge
  3. positively charge nucleus
  4. electrons on shells
  5. protons
  6. neutrons
• Order of scientists who helped history of atom:

  1. Dalton
  2. Tomson
  3. Rutherford
  4. Bohr
  5. Rutherford
  6. Chadwick
• Plum pudding model - Tomson:

  -> ball of positive charge

  -> electrons inside
• Alpha particle scattering experiment - Rutherford:

  1. fired positively charge alpha particles at thin sheet of gold
  2. most particles went through but others deflected backwards
  3. so atom has postively charged nucleus
• Metal properties:

  -> strong - bend and molded into different shapes

  -> conduct heat and electricity

  -> high melting/boiling points
• What are the group 1 elements called?


  alkali metals
• Group 1 - alkali trends (going down):

  • increased reactivity
  • lower melting/boiling points
  • higher relative atomic mass
• Why do group 1 metals increase reactivity going down?


  outer electron more easily lost as attraction between nucleus and electron decreases, as electron is further away from nucleus the further down the group
• What colour, state and toxicity are the following group 7 - halogen elements?

  • fluorine

  -> yellow

  -> gas

  -> posionous

  • chlorine

  -> green -> dense gas -> posionous

  • bromine

  -> red-brown -> volatile (easily evaporated) liquid -> posionous

  • iodine -> dark grey (solid) or purple (vapour) -> crystalline solid or vapour -> not posionous
• What are the group 7 elements called?


  Halogens
• Group 7 - halogen trends (going down):

  • less reactive
  • higher melting/boiling points
  • higher relative atomic masses
• Why do group 7 metals decrease reactivity as you go down?


  harder to gain an extra electron because outer shell is further away from nucleus
• What are group 0 elements called?


  noble gases
• Why does melting/boiling point increase as you go down?


  increase in electrons in each atom leading to greater intermolecular force to overcome
• What is a solute?


  a substance dissolved in a solvent is make a solution
• What is a solution?


  a mixture made of the solute dissolved in the solvent
• What is a solvent?


  a liquid in which another substance can be dissolved in