Atomic Structure and Chemical Properties You said that electron configurations are "the key to understanding why each element behaves the way it does." How does that work? I'll give you an example: look again at that far left group with hydrogen and the alkali metals. Start at the top and go down, clicking on each element in turn; what do you notice about the electrons? Um...well, in each one of these, the very top electron is starting a new colored row; it's all by itself in the s sublevel. Very good! The chart will tell you that the ionization energy for that element is quite small. It wouldn't take much to send that one solitary electron sailing off into dizzying freedom--and that sort of thing, electrons leaving their home atoms, leads directly to chemical reactions. So that's why the alkali metals react so violently--it's easy to set them off.

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