Subatomic Particles

• The Crookes tube is an electrical discharge tube used to investigate cathode rays.
• The Crookes Tube waas invented by William Crookes in 1869.
• The cathode rays are stream of negatively charged particles.
• Cathode


  negative electrodes
• Anodes


  Positive electrodes
• JJ Thomson


  Who discovered electrons?
• 1897


  When did JJ Thomson discovered electrons?
• corspucles


  What were electrons originally called?
• experiments with cathode ray tubes


  How did JJ Thomson discovered electrons?
• Eugen Goldstein


  Who was the first to observe the existence of protons?
• 1886


  When did Goldstein conducted an experiment using modified cathode ray tube made from a metal disk filled with holes?
• JJ Thomson


  Who discovered the nature of proton?
• James Chadwick


  Who discovered the third major subatomic particle- the neutron?
• 1932


  When did James Chadwick discovered neutrons?
• atomic number 


  • serves as the “numeric identity” of the element.
  • number of protons and electrons in an elemenet
• Mass number 


  pertains to to the sum of the numbers of protons and neutrons in an atom
• Isotopes


  atoms of the same element that have the same number of protons but different numbers of neutrons