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PERIODIC TABLE

• JOHN DALTON (1803)
  • ELEMENTS MADE OF IDENTICAL ATOMS. DIFFERENT ELEMENTS CONTAINED DIFFERENT ATOMS
• GREEK PHILOSOPHERS
• JJ THOMSON (1897)
  • POSITIVE & NEGATIVE PARTICLES. EVENLY SPREAD OUT.
• RUTHERFORD (1911)
  • FIRED ALPHA AT GOLD FOIL AND PARTICLES DEFLECTED. MOSTLY EMPTY SPACE AND POSITIVE CENTRE

ATOMS

• NUCLEUS (PROTONS, NEUTRONS) ELECTRONS AND SHELLS.
• ELEMENT IS DETERMINED BY ATOMIC NO.
• MASS Of ATOM SHOWN BY MASS NO.
• ATOMIC NO = NO PROTONS
• NO P+=NO E-
• NO. P+ = MASS NO - ATOMIC NO.