1. 1 High School Technology Initiative © 2001 Quantum History Pasteurization 1861 Albert Einstein 1905 Louis de Broglie 1924 Max Planck 1900 Columbus discovers America 1492 Ford “Model A” 1903 Niels Bohr 1913-1915Arthur Compton 1922 Erwin Schrodinger 1926 Werner Heisenberg 1925 Polio Vaccine 1952 1 st American in Space 1962 WWI 1914 – 1919 WWII 1939 – 1945 Main Menu

2. 2 High School Technology Initiative © 2001 Quantum History Max Planck Born April 23, 1858 - Died Oct. 3, 1947 German physicist Was awarded the Nobel Prize in 1918 for his discovery of energy quanta Referred to as the father of quantum physics 1900 - Planck hypothesized that there is a minimum size in which atoms can release or absorb energy. Planck’s constant 6.63 x 10 -34 J. s Frequency (s -1 ) He showed that energies must be quantized to explain the spectrum of radiation emitted from certain objects. The energy values are restricted to whole number quantities of hv.

3. 3 High School Technology Initiative © 2001 Quantum History Albert Einstein Born March 14, 1879 - Died April 18, 1955 German physicist Awarded the Nobel Prize in Physics in 1921 for his discovery of the photoelectric effect 1905 - Einstein used Planck’s quantum theory to explain the photoelectric effect. Every metal has a minimum frequency of light for which it will emit electrons. He hypothesized that the light striking the surface of the metal is a stream of tiny energy particles he called photons. The energy of each photon must be proportional to the frequency of the light.

4. 4 High School Technology Initiative © 2001 Quantum History Born Oct. 7, 1885 - Died Nov. 18, 1962 Awarded the Nobel Prize in Physics in 1922 for his investigation of atomic structure and the radiation they emanate Niels Bohr Danish physicist 1913 - Bohr developed a model of the hydrogen atom that explains its emission line spectrum. Bohr borrowed Planck’s idea that energies are quantized and proposed that only orbits of certain radii corresponding to defined energies are permitted.

5. 5 High School Technology Initiative © 2001 Quantum History A photon is absorbed when an electron moves to an orbit with a higher energy state and is emitted when an electron moves to an orbit with a lower energy state. Bohr assumed that electrons could “quantum jump” from one allowed orbit to another by absorbing or emitting photons of light with specific frequencies. Bohr’s model states that only photons of specific frequencies can be absorbed or emitted by the atom. these frequencies must correspond to the energy difference between two orbits. Bohr’s model was important because it introduced the idea of using quantized energy stated for electrons in atoms. However, his model is only accurate for atoms or ions with a single electron.

6. 6 High School Technology Initiative © 2001 Quantum History Arthur H. Compton American physicist Born Sept. 10, 1892 - Died March 15, 1962 Awarded the Nobel Prize in Physics in 1927 for his discovery of the Compton Effect 1922 - Discovered that the wavelength of x-rays would increase when they are collided with and scattered by free electrons in matter. - This increase in wavelength means that the x-ray photons can transfer quanta of energy to the electron upon collision. This was a strong verification for quantum theory because explanation of the effect required that the x-rays be looked at as particles rather than as waves.

7. 7 High School Technology Initiative © 2001 Quantum History 1924 - De Broglie proposed that an electron in its orbit around the nucleus has a particular wavelength associated with it. Born Aug. 15, 1892 - Died Mar. 19, 1987 Awarded the Nobel Prize in Physics in 1929 for his discovery of the wave nature of electrons. Louis de Broglie French physicist 1927 - Wave nature of the electron was experimentally proven using electron diffraction by Davisson and Germer. Velocity (m/s) Mass (kg) Planck’s constant 6.63 x 10 -34 J. s The wavelength of any particle is dependent on its mass and velocity.

8. 8 High School Technology Initiative © 2001 Quantum History Werner Heisenberg Born Dec. 5, 1901 - Died Feb 1, 1976 German physicist Awarded the Nobel Prize in 1932 for the creation of quantum mechanics. 1927 - Uncertainty Principle It is impossible to know both the exact momentum of an electron and its exact location in space at the same time. 1925 - Published his theory of quantum mechanics Formulated his new theory in terms of matrix equations.

9. 9 High School Technology Initiative © 2001 Quantum History Erwin Schrodinger Born Aug. 12, 1887 - Died Jan. 4, 1961 Austrian physicist Awarded a share of the Nobel Prize in Physics in 1933 for the development of his wave equation. 1926 - Wave Equation Schrodinger’s wave equation includes both the wave-like and particle-like behavior of the electron. The square of the wave function represents the probability that an electron will be in a certain place at a given instant of time.

10. 10 High School Technology Initiative © 2001 Quantum History