Lecture 09132009

Lecture 09132009 - -Plum pudding model Modeling the...

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Modern Atomic Theory -~400 B.C. Democritus proposed the theory that all matter was composed of tiny particles -Around the same time Aristotle was promoting an early iteration of the scientific method and discounted the theory because it could not be supported with empirical data -1803 John Dalton proposed an “atomic theory” with spherical solid atoms based upon measurable properties of mass Dalton’s Atomic Theory: Main points -Elements are made of tiny particles called atoms -The atoms of a given element are different from those of any other element; distinguished by relative weights -Atoms of one element can combine with atoms of other elements to form compounds Sub-Atomic Particle -JJ Thomson doing experiments with cathode ray tubes he found several atoms had very light negatively charged particles with the same charge to mass ratio -Electrons are found in all atoms -1919 Rutherford discovered the proton -Neutrons were last of the major sub-atomic particle to be discovered, by Chadwick in 1932
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Unformatted text preview: -Plum pudding model Modeling the energies-For any given electronic transition Hv = deltaE = E2 – E1 (energy of final state – energy of initial state)-Balmer Series n2 = 2 DeltaE = -2.178 x 10^-18 Rydberg equation in a hydrogen atom Z = 1 1 / lambda = E / hc = R (1/n2^2 – 1/n1^2) Quantum Mechanics-Emission and absorption spectra of gas phase atoms provide convincing evidence that the allowed energies in an atom are quantized-Yet Bohr’s model is inadequate-good results for H only-charged particles orbiting an oppositely charged particle (size weight and energy were looking at) would collapse Standing Waves-1-D standing waves-string instruments, jump ropes-2-D and 3-D standing waves Aufbau Principle “Building up principle” The orbitals of lower energy are filled in with the electrons 1 st and only then the orbitals of high energy are filled 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 5f, 6d, 5g, 6f, 6g, 6h...
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This note was uploaded on 11/18/2010 for the course CH 301 taught by Professor Fakhreddine/lyon during the Spring '07 term at University of Texas.

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Lecture 09132009 - -Plum pudding model Modeling the...

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