Basic Principles
Electron configuration describes the arrangement of electrons around an atom's nucleus following quantum mechanical principles:
- Aufbau Principle: Electrons fill lowest energy orbitals first
- Pauli Exclusion: Max two electrons per orbital, opposite spins
- Hund's Rule: Electrons in equal-energy orbitals spread out
Orbital Structure
Energy level organization:
- s-orbital: Spherical, holds 2 electrons
- p-orbital: Dumbbell shaped, holds 6 electrons
- d-orbital: Complex shapes, holds 10 electrons
- f-orbital: More complex, holds 14 electrons
Special Cases
Important exceptions and rules:
- Chromium (Cr) and Copper (Cu) exceptions
- Half-filled and fully-filled stability
- d-block and f-block anomalies
- Noble gas configurations
- Electron promotion
Applications
Understanding electron configuration helps in:
- Chemical bonding prediction
- Periodic trends
- Spectroscopy
- Oxidation states
- Magnetic properties