Midterm 2

# Midterm 2 - Study Guide for Midterm 2 Chapter 6: Major...

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Study Guide for Midterm 2 Chapter 6: Major Topics 1. electromagnetic radiation a. the emission and transmission of energy in the form of electromagnetic waves b. all electromagnetic radiation travels at the same velocity: the speed of light (c) c = 3.00 x 10 8 m/s QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. (eq. 1) 2. Bohr’s model of an atom/ Energy states of hydrogen atom a. Bohr’s model of atom included idea of electrons moving in circular orbits b. The single electron in hydrogen atom could be located only in certain orbits c. Each orbit has particular energy associated with it d. In an excited hydrogen atom, an electron originally at higher energy orbit (n = 3) falls back to lower energy orbit (n = 2). As a result, a photon with energy E = h ν (eq. 2) is given off QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. e. The energies of the electron in hydrogen atom are given by the equation: QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. (eq. 3) f. E n becomes larger in absolute value and more negative when electron nears the nucleus (n decreases) g. n = 1 : most stable energy state – ground state/ ground level h. n = 2, 3, 4,… : excited state/ excited level i. during emission, electron drops from an orbital n i to lower energy state n f j. difference between energies of initial and final states is: E = E f – E i (eq. 4) QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture. k. when a photon is emitted, n i > n f E < O (energy given off to the surrounding) l. when energy is absorbed, n i < n f E > O m. Extras i. Electron absorbs energy to “jump” to higher energy level ii. When electron falls to lower energy level, energy is emitted Example: Find wavelength (in nm) of photon emitted during transition from n i = 6 to n f = 4 state in hydrogen atom.

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QuickTime= and a TIFF (Uncompressed) decompressor are needed to see this picture. 3. The wave behavior of matter a. Louis de Broglie: matter should exhibit wave properties b. Relationship between mass and wavelength: QuickTime= and a TIFF (Uncompressed) decompressor are needed to see this picture. (eq. 7) Example: Calculate wavelength (in nm) of a hydrogen atom with mass of 1.674 x 10 -27 kg and moving at 7.00 x 10 2 cm/s. QuickTime= and a TIFF (Uncompressed) decompressor are needed to see this picture. 4. Quantum numbers In quantum mechanics, 3 quantum numbers are required to describe the distribution of electrons in atoms a. Principal quantum number, n i. Describes energy level on which the orbital resides ii. Values of n are integers 0 iii. Extras Max number of electrons = 2n 2 b. Azimuthal quantum number, l i. Defines shape of orbital ii. Values of l are integers from 0 to n-1 By example, if n = 3 3 values of l: 0, 1, 2 Value generally designated by letters s, p, d,…
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## This test prep was uploaded on 04/18/2008 for the course CHEM 121 taught by Professor Wyzlouzil during the Winter '07 term at Ohio State.

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Midterm 2 - Study Guide for Midterm 2 Chapter 6: Major...

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