AP Chemistry / Unit 1: Atomic Structure and Properties
1.5 Atomic Structure and Electron Configuration
Notes
Electrons fill orbitals by energy: $1s\,2s\,2p\,3s\,3p\,4s\,3d\dots$
- Coulomb's law: attraction grows with charge and shrinks with distance.
- Valence electrons are in the outermost shell.
Practice
The electron configuration of oxygen (8 electrons):
2 + 2 + 4.
Which electron is held most tightly?
Closest to the nucleus.
Sodium has how many valence electrons?
$3s^1$.
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