Exceptions in Writing e- Configurations of Atoms
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Exceptions in Writing e- Configurations of Atoms
Hello! At the end of lecture today, Professor Lavelle talked about 2 exceptions we need to know because we won't be able to get it from the periodic table. I got really lost and don't really understand what either of them mean, so can someone clarify?
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Re: Exceptions in Writing e- Configurations of Atoms
So when writing the configuration for Chromium, if you're simply going by the periodic table and counting, you would typically write it as [Ar] 3d^4 4s^2. The exception is that one of the electrons from the 4s is going to jump into one of the spaces in 3d because a half-filled orbital is more stable than a partial one, that's why Cr: [Ar] 3d^5 4s^1. The same rule applies for Copper, where one of the electrons from the 4s orbital fills the 3d orbital as a filled 3d orbital is more stable, thus Cu: [Ar] 3d^10 4s^1. :)
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Re: Exceptions in Writing e- Configurations of Atoms
Hi! The two exceptions are Cu and Cr, because they can form half-filled electron configurations for the 4s and 3p orbitals. The half filled orbital(1 electron in 4s and 5 electrons in 3p for Cr) is more stable than, for example, Cr, having 2 electrons in the 4s orbital and 4 electrons in 3p.
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