Electron Configuration Shortcuts

​Example: If I needed to do the configuration for Gold (Au).

​Gold has 79 electrons. Going backwards, the closest noble gas is Xenon with 54 electrons.

​Xenon ends with 5p⁶ . I need to place 25 more electrons (79-54).

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​Following the energy order, 6s comes after 5p. So I start there, placing the 25 electrons.

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[Xe] 6s² 4f¹⁴ 5d⁹

The arrangement of the periodic table reflects the last term in an electron configuration. These "blocks" of elements share the same orbital and energy level.​

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As the number of electrons increase, you can clearly see the orbital filling order by following from left to right. Also notice, each column has the same number of electrons in the final orbital.

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