C3 Part 1 - The Periodic Table

C3 Part 1 - The Periodic Table

1. PERIODIC TABLE

   • The periodic table
     • Atomic Number
       • The number of protons in an atom of an element
     • Elements arranged in order of increasing atomic number
   • Alkali metals - 1
     • The more easily the outer electron is lost, the more reactive the Group 1 element is
       • As you go down Group 1, electronic shielding increases - this means the "pull" on the outer electron from the nucleus is reduced
         • The outer electron is also further away from the positive nucleus as you go down the Group
     • Density
       • Density (gcm-3) = Mass(g)/Volume(cm3)
         • Lithium - 0.53gcm-3
         • Sodium - 0.97gcm-3
         • Potassium - 0.86gcm-3
         • Rubidium - 1.53gcm-3
         • Lithium, Sodium and Potassium will all float on water as their density is less than water (1gcm-3)
     • Low densities
     • Soft
     • Low melting and boiling point
       • As you go down Group 1 metals, the melting and boiling point of the alkali metals decrease
         • Melting point
           • Lithium - 180
           • Sodium - 97.8
           • Potassium - 63.5
           • Rubidium - 38.9
           • Caesium - 28.7
           • Francium - 27
         • Boiling point
           • Lithium - 1330
           • Sodium - 890
           • Potassium - 774
           • Rubidium - 688
           • Caesium - 690
           • Francium - 680
   • Alkali metals - 2
     • Alkali metals reacting with air (oxygen)
       • Sodium + Oxygen --> Sodium Oxide
         • 4Na+ + O2- > 2Na2O
     • Alkali metals reacting with halogens to form Alkali metal Halides
       • Sodium + Chlorine --> Sodium Chloride
         • 2Na + Cl2 --> 2NaCl
     • Alkali Metals and water
       • Sodium + Water --> Sodium Hydroxide + Hydrogen
         • 2Na + 2H2O --> 2NaOH + H2
   • The Transition Elements
     • Centre block of Periodic table
     • High Densities, Hard, Strong
     • Do not react vigorously with water
     • Frequently used as catalysts
   • The Halogens
     • As you go up Group 7, the reactivity increases
     • Diatomic molecules formed (F2/Cl2/Br2/I2)
     • Weak intermolecular bonds between the diatomic molecules
       • Low Melting point
       • Low Boiling point
     • As you go down Group 7 the melting and boiling point increase due to the intermolecular bonding between the molecules become stronger as you go down Group 7
     • Iron + Chlorine --> Iron Chloride
     • Colour
       • Fluorine - Pale Yellow
       • Chlorine - Pale Green
       • Bromine - Orange/Brown
       • Iodine - Purple Vapour
   • Organising the Elements
     • Antoine Lavaiser
       • Book
         • Lists 33 elements
         • Classifying them into gases, metals, non-metals and earths
     • Stanislac Connizzaro
       • Worked out
         • Atomic weights and listed them in a scientific paper
     • John Newlands
       • 'Law of Octaves'
         • Listed 56 elements in order of increasing atomic weight
           • Every eighth element had similar properties
     • Dmitri Mendeleev
       • Published first periodic table
         • Elements in order of atomic weights
         • In groups of similar properties
         • Predicted the elements that hadn't been discovered yet
     • Johann Dobreiner
       • Announced findings
         • Elements come in groups of three
           • Middle weight was and average of the lighter and heavier elements
     • Alexandre Chancourtois
       • Discovered
         • Elements with similar properties occur at regular intervals
     • Lothar Meyer
       • Graph
         • Volume of atom against atomic weight
           • Noticed a pattern and deduced a periodic table

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