history of the periodic table

• Aristotle- 350 bc he conclude the first elements of the periodic table are fire,earth,air,water.
• 1700 - 14 elements were known.
• 1789 - Antonie Lavoiser wrote his extensive list of 33 elements.
• 1829 -Johann Dobereiner (german chemist)noticed that Br,Cl,and I had similar properties and that Br's atomic mas was between that of Cl and I.

  He found three other groups with similarities , he called the groups triads.
• 1864 - John Newlands (english chemist ) arranged the now known 62 elements from lightest to heaviest.

  
  

  He also noticed that every 8th element had similar chemical and physical properties. their properties were repeating , this become the "Newlands Octaves."
• Lothar meyer - at the same time, he published his own table of the elements organized by increasing atomic mass.
• 1869- Dmitri Mendeleev (russian chemist ) organized the elements by atomic mass , but also made it to table form to help his students .
• Mendeleev left gaps in his table where there were missing elements.
• He mistakenly measured the mass and this would be corrected by further research , this will give to the rise to ther Periodic law, "Properties of elements are periodic functions of their atomic mass.
• 1913- Henry Moseley (English chemist) arranged elements by atomic numbers.
• Glenn T. Seaborg - After co-discovering 10 new elements , in 1944 he moved 14 elements out of the main body of the periodic table to their current location below the lanthanide series, this known as the actinide series.

  1912-1999

  discovered 8 new elements , only living person for whom an element was named.
• the elements,their names,and the symbols are given on the periodic table..
• 118 elements have been identified
• 82 elements - occur naturally on earth.
• 36 elements have beem created by scientist.
• periods/series= horizontal rows.
• groups\family= vertical columns
• metals- located to the left of the staircase line.

  *lose electrons to form + (cations)

  shiny

  ductile

  react with acid

  good conductors of heat and electricity

  most metallic element (francium).
• Non-metals - located to the right of the staircase line.

  tend to gain electrons to form - ions (anions)

  dull

  poor conductors of heat and electricicty

  good insulators

  brittle

  most reactive non-metal (fluorine)
• Mettaliods - located on and below the staircase line except At and Al.

  Tend to gain or lose electrons

  shiny and dull

  good and poor conductors of heat and electricity.

  malleable and brittle.