🧬 Electron Configuration Calculator
Fill orbitals according to the Aufbau principle and obtain noble gas shorthand instantly.
Positive charge removes electrons, negative charge adds electrons.
How to Use This Calculator
Enter atomic number
Use the periodic table to find the atomic number of the element you are studying.
Specify charge (optional)
For ions, enter the charge. Positive charges remove electrons; negative charges add electrons.
Generate configuration
Click the button to fill orbitals following the Aufbau principle, producing both full notation and noble gas shorthand.
Interpret valence shell
Use the valence shell information to discuss bonding behaviour, oxidation states, and periodic trends.
Formula
Orbitals are filled in order of increasing energy (Aufbau principle): 1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s ... respecting the Pauli exclusion principle and Hund's rule.
The calculator populates each subshell up to its capacity before moving to the next energy level. Noble gas shorthand replaces the fully filled inner configuration with the noble gas symbol enclosed in brackets.
Example: Phosphorus (Z = 15)
Full: 1s2 2s2 2p6 3s2 3p3
Shorthand: [Ne] 3s2 3p3
Example: Fe²⁺ (Z = 26, charge = +2)
Total electrons = 24 → configuration: [Ar] 3d6
Remove electrons from the highest principal quantum number first (4s before 3d) when forming cations.
Full Description
Electron configurations describe how electrons occupy atomic orbitals, underpinning chemical bonding, spectroscopy, and periodicity. This calculator automates the Aufbau filling order, delivering both expanded notation and the commonly used noble gas shorthand. By supporting ions through charge adjustments, it helps visualise how electron removal or addition alters valence shells and reactivity.
The tool is ideal for teaching environments, allowing students to experiment with different elements and immediately see the resulting configurations. Researchers and professionals can use it as a quick reference when preparing orbital diagrams, interpreting spectroscopic transitions, or validating computational output.
Use cases
- General chemistry: Reinforce periodic trends and electron shell structure.
- Inorganic chemistry: Discuss transition metal configurations and common ionic states.
- Spectroscopy: Identify possible electronic transitions from orbital occupations.
- Materials science: Evaluate valence electrons for bonding models in solids.
- Exam preparation: Practise writing configurations quickly and accurately.
Why it helps
- ✅ Immediate feedback: Generates configurations in seconds for any element up to Og.
- ✅ Noble gas shorthand: Provides compact notation used in advanced coursework.
- ✅ Ion support: Adjusts electron counts for cations and anions automatically.
- ✅ Valence insight: Highlights the outer shell for bonding discussions.
- ✅ User friendly: Clean interface optimised for classroom projection or mobile viewing.
Frequently Asked Questions
Does the calculator account for electron promotion (e.g., Cr, Cu)?
It follows the standard Aufbau order. For known exceptions where electrons promote to achieve half-filled or filled d subshells, adjust the configuration manually after using the tool.
How are ions handled?
Electrons are added or removed in order of principal quantum number, removing from the highest n first when forming cations (e.g., Fe → Fe³⁺ removes 4s electrons before 3d).
Can it display orbital diagrams?
No. The calculator outputs electron configurations in spectroscopic notation. Use the results to draw orbital diagrams manually if needed.
What is the maximum atomic number supported?
The calculator fills orbitals up to oganesson (Z = 118). Future updates may include extended subshells if new elements are confirmed.
How accurate is noble gas shorthand for ions?
Shorthand is based on electron count. For ions, removing electrons may reduce the configuration below a noble gas core. The calculator recomputes the core accordingly.