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Quantum mechanical model of the atom

Quantum mechanical model of the atom. When white light passes through a prism , a rainbow of colors is seen. Hill, J. and D. Kolb. 1995. Chemistry for Changing Times 7th ed. Phils: Prentice-Hall, Inc. http://apollo.lsc.vsc.edu/classes/met130/notes/chapter19/graphics/prism.jpg.

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Quantum mechanical model of the atom

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  1. Quantum mechanical model of the atom

  2. When white lightpasses through a prism, a rainbow of colors is seen Hill, J. and D. Kolb. 1995. Chemistry for Changing Times 7th ed. Phils: Prentice-Hall, Inc. http://apollo.lsc.vsc.edu/classes/met130/notes/chapter19/graphics/prism.jpg

  3. If a discharge of light caused by a specific element passes through a prism, only specific“lines of colors” are seen Chang, R. 2002. Chemistry 7th ed. Singapore: McGraw-Hill. Silberberg, M. 2010. Principles of General Chemistry. 2nd ed. New York: McGraw-Hill.

  4. Each element has a unique emission spectrum, just like each person has unique fingerprints • emission (or line) spectrum • pattern of lines emitted by an element Chang, R. 2002. Chemistry 7th ed. Singapore: McGraw-Hill. Silberberg, M. 2010. Principles of General Chemistry. 2nd ed. New York: McGraw-Hill.

  5. Bohr’s theory of the hydrogen atom

  6. Bohr interpreted the emission spectrum of the H atom, using the model of the atom that is based on planetary motion • Just as the planets move around the sun, the electrons move around the nucleus with specific orbits Hill, J. and D. Kolb. 1995. Chemistry for Changing Times 7th ed. Phils: Prentice-Hall, Inc. http://www.newsandevents.utoronto.ca/bios/askusimages/atomsm.jpg

  7. 1. The energy of an electron isquantized Bohr • The electron cannot have just any amount of energy; they must have specific amounts of energy • The specified energy values for an atom are called its energy levels or stationary states Hill, J. and D. Kolb. 1995. Chemistry for Changing Times 7th ed. Phils: Prentice-Hall, Inc. http://keirsey.com/personality/bohr.gif

  8. Increasing energy Silberberg, M. 2010. Principles of General Chemistry. 2nd ed. New York: McGraw-Hill.

  9. 2. An electron cangain or lose energy • If an electron gains energy, it is promoted to a higher energy level • If an electron releases energy, it is demoted to a lower energy level Hill, J. and D. Kolb. 1995. Chemistry for Changing Times 7th ed. Phils: Prentice-Hall, Inc. Chang, R. 2002. Chemistry 7th ed. Singapore: McGraw-Hill. http://keirsey.com/personality/bohr.gif

  10. 3. The energy released in these transitions shows up as a band in the emission spectrum of the hydrogen atom • Each band in the emission spectrum corresponds to a particular transition in a hydrogen atom • That is why H atom’s emission spectrum is not continuous, because the atom’s energy has only certain discrete levels or states Hill, J. and D. Kolb. 1995. Chemistry for Changing Times 7th ed. Phils: Prentice-Hall, Inc. Silberberg, M. 2010. Principles of General Chemistry. 2nd ed. New York: McGraw-Hill. http://keirsey.com/personality/bohr.gif

  11. Silberberg, M. 2010. Principles of General Chemistry. 2nd ed. New York: McGraw-Hill.

  12. Bohr’s theory cannot account for the line spectra of atoms containing more than one electron • The energy of an electron is quantized • An electron can gain or lose energy • The energy released in these transitions shows up as a band in the emission spectrum • Just as the planets move around the sun, the electrons move around the nucleus with specific orbits

  13. Quantum mechanics

  14. The electron does not orbit the nucleus in a well-defined path • Heisenberg Uncertainty (Indeterminacy) Principle • It is impossible to know both the momentum (mass * velocity) and position of a particle with certainty Chang, R. 2002. Chemistry 7th ed. Singapore: McGraw-Hill. http://osulibrary.oregonstate.edu/specialcollections/coll/pauling/bond/pictures/people/people-portrait-heisenberg.jpg

  15. We can only know the probability of finding an electron in a certain region in space • Schrödinger equation • When solved, it can describe the behavior and energies of electrons and other submicroscopic particles Chang, R. 2002. Chemistry 7th ed. Singapore: McGraw-Hill. http://www.malaspina.com/jpg/schrodinger.jpg

  16. We can only know the probability of finding an electron in a certain region in space The denser the region, the higher the probability of finding the electron Brown, , E. LeMay, and B. Bursten. 2000. Chemistry: The Central Science. 8th ed. Phils: Pearson Education Asia Pte. Ltd.

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