Electron Configurations and Orbital Rules for Chemistry

Electron Cloud

Regions where electrons move around the nucleus.

Energy Levels

Divisions of the electron cloud represented by n = 1, 2, 3, ....

Sublevels

Divisions within energy levels that include s, p, d, and f orbitals.

s orbital

1 orbital that can hold 2 electrons.

p orbital

3 orbitals that can hold 6 electrons.

d orbital

5 orbitals that can hold 10 electrons.

f orbital

7 orbitals that can hold 14 electrons.

Orbital Capacity Rule

Each orbital holds a maximum of 2 electrons with opposite spins.

Aufbau Principle

Electrons fill the lowest-energy orbitals first.

Order of Filling Orbitals

1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p (diagonal rule).

Pauli Exclusion Principle

Each orbital holds a maximum of 2 electrons with opposite spins.

Hund's Rule

Electrons spread out in orbitals of equal energy before pairing.

Electron Configuration

Shows how many electrons go into each sublevel.

Orbital Diagram

Visual representation showing arrows in boxes for each orbital.

Noble Gas Configurations

Shorthand way of writing electron configurations using noble gases.

Format for Noble Gas Configurations

[Noble Gas] + remaining configuration.

Stability Rule

Full sublevel (s², p⁶, d¹⁰) = most stable; Half-full sublevel (s¹, p³, d⁵) = stable.

Max Electrons Formula

Max electrons per energy level is given by 2n².

Sublevel Capacities

s → 2, p → 6, d → 10, f → 14.