This video reviews the types of orbitals and shows how we can count electrons and place them in orbitals using the periodic table.
Electron configurations describe where electrons are located around the nucleus of an atom. For example, the electron configuration of lithium, 1s²2s¹, tells us that lithium has two electrons in the 1s subshell and one electron in the 2s subshell.
Source: Khan Academy, https://youtu.be/LyFzELsUgBU
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