The Atom

• Dalton’s Atomic Theory: All matter is made up of indivisible atoms which cannot be created or destroyed.
• William Crookes discovered the Electron. Cathode ray tube.
• JJ Thomson determined that electrons were negative. Found E/M ratio.
• Robert Millikan’s Oil drop experiment discovered size of electron’s charge.
• Plum Pudding Model: Solid positive sphere with electrons embedded.
• Rutherford discovered the Nucleus. Fired alpha particles at gold foil. Proton.
• Chadwick discovered the neutron by firing alpha particles at beryllium.
• Energy level is the fixed energy value that an electron in an atom may have.
• Heisenberg’s Uncertainty Principle states that it is... (More)