PHY SCI

• Atoms


  Tiny indivisible particles that make up all matter
• Plato

  • Introduced the concept of atoms having geometric shapes
• Democritus


  • Introduced the concept of atoms being separated by empty space
• Leucippus


  • Introduced the concept of atoms being indivisible units of matter
• Aristotle


  • Said that balance between the four elements can be obtained
• Phosphorus


  • The first element in the periodic table to be discovered in a serendipitous event
• Our understanding of the model of atom continues to evolve
• Recent discoveries and developments are made, giving us the glimpse of what atoms look like
• Let us leave Alchemy behind and focus on modern chemistry
• John Dalton


  A British teacher in the late 1700's who combined the ideas of elements by the ancient Greek philosophers with that of atoms
• Dalton's Atomic Theory


  • All matter is made of tiny indivisible particles called atoms

  2. Atoms of the same element are identical

  3. Atoms combine to form compounds in simple whole number ratio

  4. Chemicals reactions involve the rearrangement of atoms; no matter is created nor destroyed
• Billiard Ball Model


  A model that represents atoms as solid, indivisible spheres
• We already have subatomic particles: Proton, Electron, Neutron
• Michael Faraday


  • Matter must contain positive and negative charges

  2. Opposite charges attract, like charges repel

  3. Atoms combines to form compounds because of their attraction to one another
• Faraday's new model explained the presence of charges in matter, and how atoms group into compounds and molecules
• Faraday did not explain where these charges came from, or how they got into the atom
• J.J. Thompson


  • Atoms contains electrons

  2. Electrons have a very little mass and have a negative charge

  3. The rest of the atom is positive

  4. Electrons are stuck throughout the atom randomly

  5. Electrons can be added or removed from atoms to give them positive and negative charges
• Thompson's new model explained how charge was transferred between atoms, and why they might have these charges
• Thompson's model did not fully explained how positive and negative charges stayed separate
• Gold Foil Experiment


  An experiment that showed a positively-charged beam often passes through a thin sheet of gold without interference, but once in a while beam bounced off as if it hit something solid
• Rutherford's Nuclear Model


  • Atoms are made of 3 particles: Electron, Proton, Neutron

  2. The nucleus contains all of the positive charges and most of the mass

  3. The nucleus is tiny compared to the rest of the atom

  4. The electrons orbit the nucleus like plates around the sun

  5. The mass of the electron is 1/1800th the mass of the proton

  6. The size of the atom is determined by the furthest electron from the nucleus

  7. There is only empty space between the nucleus and the electrons
• Rutherford knew his model was incomplete, but without more data he could not figure out what was missing
• Marie Curie


  Coined the term "Radioactivity" and discovered the elements Polonium and Radium. She was awarded the Nobel Prize for Physics and Chemistry for her works.
• Niels Bohr


  The father of Quantum Theory who proposed that electrons have orbits around the nucleus and can only exist at given energy levels
• Energy Level


  Where an electron is likely to be moving
• Niels Bohr


  • Further dissected the parts of an atom into two regions: The Nucleus (contains Protons and Neutrons, almost all of the mass) and the Electron Cloud (most of the volume of an atom, region where electrons can be found)