periodic table

• electronic configurations across period :

  • the period number corresponds with the valence shell number (eg. elements in period 2 will have 2 valence shells)
• electronic configurations down a group :

  • elements in the same group have the same number of valence electron shells (eg. group 1 metals all have 1 valence electron)
• elements with the same number of electrons have similar chemical properties
• there is a decrease in metallic properties and an increase in non-metallic properties across a period
• metallic properties of elements down a group :

  • going down a group the element's metallic properties increase. Since the site of the atom increases down the group, the outermost electrons will be further away from the attractive molecules
• elements in grp 1,2 & 3 :

  • metals
  • lose electrons to form positive ions
• element in grp 14 :

  • share electrons to form covalent bonds
• elements in grp 15 - 17 :

  • share electrons to form covalent bonds
  • gain to form negative ions with metals
• physical properties of group 1 metals (alkali metals) :

  • soft and can be cut easily (when cut has a silvery and shiny surface that rapidly tarnishes in air)
  • have low melting and boiling points (below 200 degrees unlike other metals)
  • have low densities (Li,Na and K float on water)
  • going down the group (the melting points of the alkali metals decreases and the densities generally increase)
• chemical properties of group 1 metals (alkali metals) :

  • highly reactive (stored in oil)
  • reactivity increases down the group
  • reactions of alkali metals with water (eg. 2Li (s) + 2H2O (l) -> 2LiOH (aq) + H2 (g) )
• order of reactivity of group 1 metals :

  (least reactive) lithium -> sodium -> potassium -> rubidium -> caesium -> francium (most reactive)
• physical properties of group 17 metals (halogens) :

  • low melting and boiling points
  • are coloured
  • as the melting points increase -> the colours become darker
• colours of metals :

  1. chlorine -> yellow-green gas
  2. bromine -> red-brown liquid
  3. iodine -> purple-black solid
• chemical properties of group 17 elements :

  • halogens react with most metals to form halides
  • a more reactive halogen will displace a less reactive halogen from its halide solution
• order of reactivity of group 17 halogens :

  (most reactive) flourine -> chlorine -> bromine -> iodine -> astatine -> tenessine (least reactive)
• group 18 elements :

  • monoatomic non-metals
  • colourless gas at r.t.p
  • low melting and boiling points
  • insoluble in water
  • unreactive
• transition metals :

  • high melting and boiling points (in the thousands)
  • high density (sink)
  • variable oxidation states
  • also function as catalysts for many reactions
• oxidations states :

  chromium -> +3, +6

  manganese -> +2, +4, +7

  iron -> +2, +3

  copper -> +1, +2
• colours of common compounds :

  chromium (ii) chloride - green

  potassium dichromate (iv) - orange

  iron (ii) sulfate - pale green

  iron (ii) chloride - yellow

  manganese (iv) oxide - brown/black

  potassium manganate (vii) - purple

  copper (i) oxide - red

  copper (ii) oxide - black