The Periodic Table

• Groups 1,2,3:

  • metals
  • lose electrons to form ions
• group 4:

  • non-metals
  • don't tend to form ions
• groups 5,6,7:

  • gain electrons to form ions
• group 8/0:

  • non-metals
  • don't form ions
  • full outer shell
• History of Periodic Table:

  • 1808 - John Dalton arranged elements in order of mass
  • 1817 - Johann Döbereiner put forward law of triads
  • 1864 - John Newlands produced Law of Octaves
  • 1869 - Dmitri Mendeleev used Newlands' table and left gaps for undiscovered elements
• Alkali metals (group 1):

  • soft metals
  • fizz (in water)
  • move (in water)
  • changed pH of solution
  • Down the group: (in water)
  • more fizzing
  • more moving
  • bigger atom; more reactive
  • more vigorous
• Noble Gases: (group 0/8)

  • not very reactive - full outer shell
  • colourless
  • odourless
  • density increases down the group
  • coloured glow when electricity runs through them
• Halogens (group 7):

  • 7 electrons on outer shell
  • non-metals
  • diatomic molecules (travel in pairs)
  • Down the group:
  • relative molecular mass (mass of molecule) increase
  • melting point increase
  • boiling point increase
  • reactivity DEcrease
• a more reactive halogen can displace a less reactive one from an aqueous solution of its salt
• Reaction between alkali metal and halogen:

  alkali metal + halogen → alkali metal halide
• Transition Metals:

  • Compared to group 1
  • higher melting point
  • denser
  • harder
  • stronger
  • less reactive
  • Special Properties
  • form coloured compounds
  • important catalysts
  • form ions with different charges
• History of The Atomic Structure:

  1897 - JJ Thompson - electron discovered - plum pudding model

  1911 - Rutherford - gold foil experiment - nucleus discovered

  1913 - Bohr - shells discovered

  1932 - James Chadwick - neutron discovered