Electron Configuration Calculator
Determine electron distribution in atomic orbitals using Aufbau principle
Calculate Electron Configuration
Choose from periodic table elements
Number of protons (1-118)
0 for neutral atom, + for cation, - for anion
Choose display format
Electron Configuration Results
Element Information
Electron Configuration
Valence Information
Orbital Diagram (Simplified)
Key Principles
Example: Carbon Electron Configuration
Given Information
Element: Carbon (C)
Atomic Number: 6
Electrons: 6 (neutral atom)
Step-by-Step Configuration
1. Fill 1s orbital: 1s² (2 electrons)
2. Fill 2s orbital: 2s² (2 electrons)
3. Fill 2p orbital: 2p² (2 electrons, following Hund's rule)
Final Configuration: 1s² 2s² 2p²
Shorthand: [He] 2s² 2p²
Valence Electrons: 4 (2s² 2p²)
Orbital Filling Order
Based on Aufbau principle - electrons fill lowest energy orbitals first
Orbital Capacity
Quick Tips
Noble gas shorthand saves writing
Valence electrons determine bonding
Some elements have irregular configs
Cations lose electrons first
Anions gain electrons last
Understanding Electron Configuration
What is Electron Configuration?
Electron configuration describes the distribution of electrons in an atom's orbitals. It follows specific rules that determine the most stable arrangement of electrons around the nucleus.
Key Components:
- • Energy Level (n): Principal quantum number (1, 2, 3...)
- • Orbital Type: s, p, d, f subshells
- • Electron Count: Superscript showing electrons in orbital
- • Spin Pairing: Up and down arrows in orbital diagrams
Fundamental Principles
Aufbau Principle
Electrons fill orbitals of lowest energy first, following the orbital energy sequence.
Hund's Rule
Electrons occupy degenerate orbitals singly before pairing, maximizing unpaired electrons.
Pauli Exclusion
No two electrons can have identical quantum numbers; paired electrons have opposite spins.
Configuration Exceptions
Chromium (Cr)
Expected: [Ar] 3d⁴ 4s²
Actual: [Ar] 3d⁵ 4s¹
Half-filled d subshell is more stable
Copper (Cu)
Expected: [Ar] 3d⁹ 4s²
Actual: [Ar] 3d¹⁰ 4s¹
Filled d subshell is more stable
Gold (Au)
Expected: [Xe] 4f¹⁴ 5d⁹ 6s²
Actual: [Xe] 4f¹⁴ 5d¹⁰ 6s¹
Relativistic effects and stability
Applications in Chemistry
Chemical Bonding
Valence electrons determine how atoms bond:
- • Ionic bonds: electron transfer
- • Covalent bonds: electron sharing
- • Metallic bonds: electron sea model
- • Coordination compounds
Periodic Trends
Configuration explains periodic properties:
- • Atomic radius patterns
- • Ionization energy trends
- • Electronegativity values
- • Magnetic properties