Overview
Explains how to write electron configurations using the aufbau principle and the periodic table.
Writing Electron Configurations
- Electrons fill atomic orbitals from lowest to highest energy.
- Each subshell is filled before moving to the next higher one.
- The aufbau principle ("build up" in German) guides the order: start at 1s, then 2s, 2p, 3s, 3p, 4s, 3d, 4p, etc.
Using the Periodic Table
- Each row (period) represents a shell (principal quantum number, n).
- s-block: groups 1 and 2; p-block: right side; d-block: transition metals; f-block: lanthanides and actinides.
- s and p blocks match the period number for n; d is one behind; f is two behind.
Applying the Aufbau Principle
- Fill orbitals by reading the periodic table left to right, top to bottom.
- Typical order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, etc.
- Use the periodic table or orbital diagrams to remember the order.
Key Terms & Definitions
- Electron Configuration: Arrangement of electrons in orbitals.
- Aufbau Principle: Electrons fill lowest energy orbitals first.
- Subshell: Group of orbitals (s, p, d, f).
- Principal Quantum Number (n): Main energy level.
Action Items / Next Steps
- Practice writing electron configurations using the periodic table and aufbau principle.
- Memorize how period numbers relate to s, p, d, and f orbitals.