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II. Bohr Model of the Atom

Electrons in Atoms. II. Bohr Model of the Atom. A. Bohr Model. Niels Henrik David Bohr 1885 - 1962 Born 1885, Copenhagen, Denmark. Father was an eminent physiologist. 1911 - Studied and worked at Cambridge under Sir JJ Thomson

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II. Bohr Model of the Atom

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  1. Electrons in Atoms II. Bohr Model of the Atom

  2. A. Bohr Model • NielsHenrik David Bohr 1885 - 1962 • Born 1885, Copenhagen, Denmark. • Father was an eminent physiologist. • 1911 - Studied and worked at Cambridge under Sir JJ Thomson • 1912 – worked in Ernest Rutherford’s lab in Manchester, England. • 1922 – Nobel Prize in Physics for work on the structure of atoms.

  3. A. Bohr Model • e- exist only in orbits with specific amounts of energy called energy levels • Therefore… • e- can only gain or lose certain amounts of energy • only certain photons are produced

  4. B. Line-Emission Spectrum excited state ENERGY IN PHOTON OUT ground state

  5. Energy of photon depends on the difference in energy levels Bohr’s calculated energies matched the IR, visible, and UV lines for the H atom B. Line-Emission Spectrum 6 5 4 3 2 1

  6. B. Line-Emission Spectrum • Each element has a unique bright-line emission spectrum. • “Atomic Fingerprint” Helium • Bohr’s calculations only worked for hydrogen! 

  7. Electrons in Atoms III. Quantum Model of the Atom

  8. A. Electrons as Waves • Louis de Broglie (1924) • Applied wave-particle theory to e- • e- exhibit wave properties QUANTIZED WAVELENGTHS

  9. VISIBLE LIGHT ELECTRONS A. Electrons as Waves EVIDENCE: DIFFRACTION PATTERNS

  10. B. Quantum Mechanics • Heisenberg Uncertainty Principle • Impossible to know both the velocity and position of an electron at the same time

  11. B. Quantum Mechanics • SchrödingerWave Equation (1926) • finite # of solutions  quantized energy levels • defines probability of finding an e-

  12. Radial Distribution Curve Orbital B. Quantum Mechanics • Orbital (“electron cloud”) • Region in space where there is 90% probability of finding an e-

  13. B. Quantum Mechanics • Summary of Quantum Theory • Describes mathematically the wavelike properties of e-1 and other small particles. • Applies to ALL atoms (unlike the Bohr model) • Supports the idea that e-1 exist in regions called orbitals where there is a probability of finding them. • Ask me about the 4th bullet point

  14. B. Quantum Mechanics • Organization of electrons in atoms • Energy levels • Sublevels • Orbitals

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