Science Unit 4 Part 2

Order 

• God is a God of order and man, created in the image of God seeks to find order as well
• The Periodic Table is the result

Dmitri Mendeleev's Periodic Table

• 1860's
• Made a "deck of cards" w/ elements
• Lined up elements in order of increasing mass- a pattern emerged 
• ROWS- increasing mass/columns-similar properties

Mendeleev's Prediction

• His table was incomplete because not all elements had been discovered

Evidence Supporting Mendeleev's Table

• Later on Germanium, Gallium, and Scandium were discovered

Henry Moseley's Table

• In, 1913, used x-ray, to measure positive charge (i.e. atomic #) and the elements were prearranged accordingly

Organization of Table

• Periods:
  • Each of seven rows is a period
  • Valence electrons increase by one across period
    • Electrons int he outermost shell/energy level
    • Determines how reactive an element is 
• Groups:
  • Each of 18 columns is a group or family 
  • All elements in column have similar properties

• 4 pieces of info for each element
  • name
  • symbol
  • atomic #
  • atomic mass
•     Atomic mass depends on distribution of element's isotopes in nature and masses of those isotopes (weighted average)