Atkins’ Physical Chemistry Eighth Edition Chapter 8 Quantum Theory: Introduction and Principles Copyright © 2006 by Peter Atkins and Julio de Paula Peter Atkins Julio de Paula

“Mysteries” of classical physics Phenomena that can’t be explained classically: 1.Blackbody radiation 2.Atomic and molecular spectra 3.Photoelectric effect

Fig 8.15 Davisson-Germer experiment (1925)

Comment 8.4 pg 252 Constructive and destructive interference

Fig 8.16 de Broglie relationship between momentum and (matter) wavelength Wave-Particle Duality for: Light and Matter

Fig 8.17 TEM image of the cross-section of a plant cell

Dynamics of a microscopic system The wavefunction Ψ replaces the classical trajectory (particle is distributed through space) The wavefunction Ψ replaces the classical trajectory (particle is distributed through space) Ψ contains all the dynamical information about the system it describes (i.e., energy and approx. location) Ψ contains all the dynamical information about the system it describes (i.e., energy and approx. location) Ψ is a math function, e.g., sin x, e -x, etc. Ψ is a math function, e.g., sin x, e -x, etc.

Time-independent Schrodinger equation for particle of mass m moving in one dimension, x: Since particle is moving, QM says its wavefunction is complex: where the solution is: We can use relationship To write

Fig 8.18 Real and imaginary part of the Ψ(x) of a free particle moving in the positive x direction

Fig 8.29 Integral of the function f(x) = (sin x)(sin 2x) sin x sin 2x