Orbital Diagrams

Full Periodic Table (1 - 118)

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Interactive Lab Tools

Electron Balance 0 / 6 e⁻

Rule Academy

Master the quantum principles governing how elements arrange their electrons under strict Madelung systematic ordering.

Aufbau Principle

Electrons occupy the **lowest energy orbitals available** first.

Madelung: 1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s < 5f < 6d < 7p

Hund's Rule

For degenerate orbitals (such as $2p$ or $3d$), place one electron in each orbital **with parallel spin** before double-occupying any.

Students must fill singly (with matching ↑ spins) before pairing up ↓ spins.

Pauli Exclusion

No two electrons can share the same set of four quantum numbers. A single orbital slot holds **at most two electrons**, and they **must have opposite spins** ($\uparrow\downarrow$).

Same-spin pairs ($\uparrow\uparrow$ or $\downarrow\downarrow$) are physically impossible!

Standard Madelung's Order

Historically, some elements showcase exceptions to the filling rule due to subshell half/full stabilization (e.g. Copper, Chromium). To match high school textbook introductory curriculums, this lab strictly follows the **idealized Madelung systematic Aufbau path** (diagonal rule) with no transitional exceptions.

Electron Configuration Notation

Automatically calculated as you populate subshells below.

Aufbau Hund's Z-Match

Standard:

Shorthand:

Orbital Diagram

(Click left for Spin Up ↑, right for Spin Down ↓ inside boxes)

↑ Single Up ↑↓ Paired

INCREASING ENERGY

Orbital Orbit