Atomic Structure

• Thales, Anaximenes, Heraclitus - stated primal matter made up of matter
• Aristotle - stated all materials are composed of four elements
• Democritus and Leucippus - proposed that matter is composed of very tiny particles that cannot be further divided
• John Dalton - suggested atoms were the smallest unit of an element
• Joseph John Thompson experiments with Cathode Ray Tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons
• Name where each charged plates are located

  A) negative plate

  B) positive plate

  
• Based on the picture, where did the charge attract?

  Positive Plate
• Thompson's plum pudding model of the atom had negative charged electrons embedded within a positive charged nucleus
• Robert Millikan's Oil drop experiment to measure the charge of an atom
• who are the two scientists that performed the oil drop experiment?

  Robert Millikan

  Harvey Fletcher
• Ernest Rutherford and his team performed the alpha scattering experiment where he bombarded positive charged alpha particles to a thin gold foil
• Neil Bohr used Max Planck's Theory on quantized energy of the energy of electrons
• Ernest Rutherford also discovered protons
• James Chadwick discovered the neutron in 1932
• Bohr discovered two state of electrons: ground state and excited state.
• Ground state - State that is stable in energy
• Excited state - state that absorb energy and move to a higher energy level
• Atomic number - distinctive number of protons
• Mass number is the sum of the number of protons and neutrons
• Identify the label in the picture

  A) Mass number

  B) Atomic number

  
• How to get the atomic number?

  Number of protons or electrons
• How to get the mass number?

  Mass=protons + neutron
• How to get neutron?

  Neutron = Mass - Number
• Identify the labels

  A) Mass number

  B) Symbol

  C) Atomic number