L07 Chem 111A Lecture 5: Chem Week 5 - end of exam1 stuff
25 Sep 2015
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First seen independently by gp thomson and davisson in 1927. Atomic spacings in crystals are on the order of 120 pm. The gaps between atoms create slits for electron diffraction. Used al crystal (atomic spacing 280 pm) therefore diffraction occurs and electron waves can combine according to the superposition principle. The rings >> bright spots and dark spots provided solid evidence of diffraction and constructive and destructive interference obtained the. Macroscopic objects have wave character, but their wavelengths are too small for the diffraction to be observed. Everything has matter waves associated with its motion. Quantum mechanics says everything has both wave and particle characteristics. Heisenberg uncertainty principle: 1927: because of the wave character of matter, precise, simultaneous determination of the position and momenta ( ) of small particles like electrons are impossible. Calculate the minimum uncertainty in position for an electron in an h atom in te ground state. If the momentum is known within 10% overall.
