Ch 7 quantum mechanics

Ch 7 quantum mechanics - Chapter 7 The Quantum Mechanical...

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Chapter 7 : The Quantum Mechanical Model A. 7.1 Intro a. classical mechanics (physics)—laws describing motion of macroscopic objects b. quantum mechanics (chem.) –principles of electrical + magnetic properties at atomic + subatomic level c. quantum-mechanical model —model that explains how electrons exist in atoms and how those electrons determine the chemical/physical properties of elements B. 7.2 Electromagnetic radiation a. all electromagnetic radiation travels at speed of light b. electromagnetic radiation —type of energy embodied in oscillating electric + magnetic fields b.i. electric field = region of space where electrically charged particle experiences a force b.ii. magnetic field = region of space where a magnetic particle experiences a force b.iii. amplitude = vertical height of a crest (from middle to top) b.iv. wavelength = distance between adjacent crests b.v. ^both are related to quantity of energy carried by a wave c. as wavelength decreases, frequency increases + vice versa c.i. where λ = meters and ν = s -1 (hertz) c.ii. visible λ = 400 nm – 700 nm d. all electromagnetic radiation travels in waves; waves have 3 basic characteristics d.i. wavelength (λ) –the distance b/w the crests or troughs of a wave d.ii. frequency (nu, ν) – the number of waves/cycles per second passing a certain point (Hz = 1 cycle per second) d.iii. speed (c) – all electromagnetic radiation ahs same speed, speed of light d.iii.1. c = 2.9979 x 10 8 m/s e. Electromagnetic spectrum : electromagnetic radiation is classified based on λ e.i. 10 -12 = gamma rays = not good for you (only exposed in radioactivity)— shortest wavelength e.ii. 10 -10 x-rays e.iii. 10 -8 ultraviolet = tanning e.iv. 400 nm to 750 nm = visible light (violet/blue = 400 nm, red = 750 nm) e.iv.1. different amplitudes affect diff brightness e.iv.2. diff wavelengths = diff colors e.v. 10 -4 = infrared (thermal radiation=heat) 10 -2 = microwaves e.vii. 1 – 10 4 = radiowaves (1=FM, 10 2 =shortwave, 10 4 = AM) f. chemiluminescence : exothermic rxn that emits light and little to no heat f.i. ex) Fireflies = release energy as light not heat, so don’t burn up f.ii. ex 2. luminol rxn: luminol + 2 h 2 O 2 luminol* light + 2H 2 O + O 2 f.iii. most exothermic = release heat to surroundings f.iv. products are formed in an excited electronic state; they decay into an electronic ground state thru fluorescence or phosphorescence g. interference : waves interacting w/ one another in phase or out of phase
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g.i. constructive interference – two waves in phase add to make a larger wave (amplitude increases, not frequency or wavelength) g.ii. destructive interference – waves are exactly out of phase to cancel each other out h. diffraction – waves (not particles) bend around an opening in a barrier h.i. waves act like crests + diffract thru a barrier h.ii. particles don’t diffract and simply go straight h.iii.
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This note was uploaded on 02/17/2012 for the course CHEM 105ALg taught by Professor Bau during the Spring '07 term at USC.

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Ch 7 quantum mechanics - Chapter 7 The Quantum Mechanical...

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