Electron Configuration Study Guide

Electron Configuration

- “address” for the electrons in an atom'

→ Quantum Mechanical Model

• Electrons are in electron clouds surrounding the nucleus

• Probability of finding electrons in a given area

Guide to Electron Configuration

1. principle energy level: 1-7 (Rows on P. Table; electron energy levels)

2. Sublevel: s, p, d, f

   - electron clouds

3. Orbital: specific area of probability in an electron cloud (sublevel) ***Shape

Short Electron Configuration

• Takes Noble gas before the element'

• Write out remaining configuration (valence)

ex…

Fe (Iron):

Long →1s²2s²2p⁶3s²3p⁶4s²3d⁶

Short → [Ar] 4s² 3d⁶

Aufbau Principle

electrons fill lowest energy orbitals first

Pauli Exclusion Principle

electrons sharing an orbital have opposite spin (reduce repulsion)

Hund’s rule

electrons will go into empty orbitals before pairing up