1. Quantum Physics   Quantum   The smallest quantity of a substance that still has the specific properties of that substance Discrete vs. Continuous   Albert Einstein showed that light is quantized and contains photons Packets of energy 12/16/2015APHY1011

2. Quantum Physics   Balmer Series   How did physicists determine that the energy levels of electrons are quantized? Isaac Newton – prism and sunlight → light is a wave Interference patterns like with water → light is a wave Joseph von Fraunhofer – the Sun’s spectrum has gaps → ? Observations of gas emission and absorption spectrum → ?   J. J. Balmer develops an equation that analyzes the pattern on the spectral lines that are observed. 12/16/2015APHY1012

3. Quantum Physics 12/16/2015APHY1013

4. Quantum Physics   Photons   Max Planck showed how the radiation emitted or absorbed by an object was quantized but still thought of light as a wave. Einstein showed that photons have energy E = hf Confirmed though experimentation by Robert Millikan   Since h = 6.63 x 10 -34 Js, each photon carries a very small amount of energy 12/16/2015APHY1014

5. Quantum Physics   Photoelectric Effect   Shining light on metal could cause electrons to be ejected from the metal. This could not be explained using the wave theory of light   Einstein’s photon theory of light explained the observations concerning the ejection of electrons from metals. Waves vs. Photons 12/16/2015APHY1015

6. Quantum Physics   The Bohr atom   Thomson, Rutherford and Millikan discover the structure of the atom   Classical EM theory could not explain this structure   Niels Bohr developed a model of the atom where the electrons had certain stable states that had quantized radii and energy Bound states of the electron in hydrogen 12/16/2015APHY1016

7. Quantum Physics   Energy levels, photons and spectral lines   Bohr’s model of the atom matches the observations of spectral lines from hydrogen “Jumping” of the electron between energy levels   Einstein and Planck explained how a photon is emitted or absorbed by an atom 12/16/2015APHY1017

8. Quantum Physics   Energy levels, photons and spectral lines 12/16/2015APHY1018

9. Quantum Physics   Energy levels, photons and spectral lines 12/16/2015APHY1019

10. Quantum Physics   Energy levels, photons and spectral lines   Louis de Broglie showed that electrons are standing waves that have mass and charge They overlap the Bohr “orbits” Explains why electron energy levels are quantized and why electrons do not spiral into the positive nucleus 12/16/2015APHY10110

11. Quantum Physics   Energy levels, photons and spectral lines 12/16/2015APHY10111

12. Quantum Physics   Elements   Many substances but few “building blocks” Think of the number of words and letters in English   The Periodic Table Tells us about the structure of elements and how they behave 12/16/2015APHY10112

13. Quantum Physics   Elements   Metals, nonmetals and metalloids Hydrogen is different than the others   Most elements are found in combination with other elements 12/16/2015APHY10113