Monday, 12 January 2015

2a) The Periodic Table

Origins of the periodic table


  1. Newland's Octaves:
    • elements in groups have similar properties 
    • didn't leave gaps for undiscovered elements 
    • metals and non metals are mixed up
  2. Mendeleev 
    • arranged by mass
    • left gaps 
    • some elements in wrong order 
    • now arranged in order of atomic number 
LHS metals                                                                                                                  RHS Non-metals 

Groups- elements that have the same number of outer shells are part of the same group
              They have similar chemical properties and physical appearance is similar 

Periods- number of electrons or protons increases across period recurring patterns 

Transition Elements
  • metals 
  • hard/strong
  • high melting points 
  • unreactive
  • act as a catalyst 
  • form a coloured compound 
  • 3rd shelll being filled across period 

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