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Unformatted text preview: Chem 260 Fall 2009 Assignment 8. This is an old assignment that I’m reusing. You can calculate term symbols many different ways. Take a look at your notes and see how it has been suggested there. Then try the method below – it involves matrices which make it easy to see what is happening (at least to me!). Notice that in the answers, some of the tables continue on a second page. As long as you come up with the same answers, it doesn’t matter which method you use. See http://hyperphysics.phyastr.gsu.edu/hbase/quantum/hydfin.html for an example of hyperfine splitting. Here is another way to think about determining term symbols. To determine the states(terms) of a given atom or ion: 1. Write down the electronic configuration (ignore closed subshell electrons) 2. Determine the number of distinct microstates that can represent that configuration. If you have e electrons in a single open subshell of 2l+1 orbitals, this value is #microstates = (2 (2l+1) )!/ e !(2 (2l+1) e )! 3. Tabulate the number of microstates that have a given M L and M S 4. Decompose your table into terms by elimination 5. Test the total degeneracy of the resultant terms to account for all the microstates counted in parts 2 and 3 6. Determine the lowest term for the configuration by Hund’s Rules. Questions for term symbols: 1. Consider a carbon atom with 2 p electrons that can go into three orbitals. There are 15 possible combinations. Determine the combinations with the highest and lowest values of M S and the highest and lowest combinations of M L . Would any of these be the ground state? 2. H(1s 1 ) 3. He(1s 2 ) 4. He(1s 1 2s 1 ) (an excited state configuration) 5. B(1s 2 2s 2 2p 1 ) 6. C(1s 2 2s 2 2p 2 ) 7. What are the atomic state term symbols resulting from the lowest energy configuration of N (1s 2 2s 2 2p 3 )?...
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 Spring '08
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 Math, Matrices, Atomic orbital, ml, ground state, D. Ms, P. MS

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