Electron Configuration Generator - Interactive Chemistry Tool
Generate electron configurations for any element instantly with our free interactive tool. View configurations in noble gas notation or full notation, see orbital diagrams with box notation, and explore ion configurations. Perfect for chemistry students and educators.
Features
- ⚛️ All Elements: First 56 elements plus common exceptions (Au, Hg)
- 📝 Two Notations: Full configuration and noble gas shorthand
- 📊 Orbital Diagrams: Visual box notation with up/down arrows
- ⚡ Ion Configurations: Calculate for cations and anions
- ⚠️ Exception Alerts: Highlights Cr, Cu, and other anomalies
- 🔍 Quick Search: Find by name, symbol, or atomic number
Understanding Electron Configuration
Aufbau Principle
Electrons fill lowest energy orbitals first: 1s → 2s → 2p → 3s → 3p → 4s → 3d...
Pauli Exclusion
Maximum 2 electrons per orbital with opposite spins (↑↓)
Hund's Rule
Electrons spread out before pairing in degenerate orbitals
Maximum Electrons
s: 2, p: 6, d: 10, f: 14 electrons per subshell
Orbital Filling Order
1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s → 4d → 5p → 6s → 4f → 5d → 6p → 7s → 5f → 6d → 7p
⚠️ Common Exceptions
Some elements don't follow the expected filling order due to extra stability of half-filled or fully-filled d subshells:
- • Chromium (Cr): [Ar] 4s¹ 3d⁵ (not 4s² 3d⁴)
- • Copper (Cu): [Ar] 4s¹ 3d¹⁰ (not 4s² 3d⁹)
- • Silver (Ag): [Kr] 5s¹ 4d¹⁰
- • Gold (Au): [Xe] 6s¹ 4f¹⁴ 5d¹⁰
Block Types
Groups 1-2
Groups 13-18
Transition metals
Lanthanides/Actinides
Perfect For
- 📚 High school and AP Chemistry students
- 🎓 College chemistry coursework
- 👨🏫 Teachers creating lesson materials
- 🔬 Understanding periodic table trends
- 📝 Homework and exam preparation
Frequently Asked Questions
What is electron configuration?
Electron configuration describes how electrons are distributed among the orbitals of an atom. It follows specific rules: electrons fill lower energy orbitals first (Aufbau principle), each orbital holds max 2 electrons with opposite spins (Pauli exclusion), and electrons spread out before pairing (Hund's rule). Example: Carbon is 1s² 2s² 2p².
What is noble gas notation?
Noble gas notation (or core notation) is a shorthand where the electron configuration of the nearest noble gas is written in brackets, followed by remaining electrons. For example, Sodium (Na) is [Ne] 3s¹ instead of 1s² 2s² 2p⁶ 3s¹. This makes longer configurations easier to read.
Why are Chromium and Copper exceptions?
Chromium (Cr) and Copper (Cu) don't follow the expected filling order because half-filled (d⁵) and fully-filled (d¹⁰) d subshells are exceptionally stable. Chromium is [Ar] 4s¹ 3d⁵ (not 4s² 3d⁴), and Copper is [Ar] 4s¹ 3d¹⁰ (not 4s² 3d⁹). This extra stability comes from exchange energy.
What are valence electrons?
Valence electrons are electrons in the outermost shell that participate in chemical bonding. For main group elements, valence electrons are in the highest s and p orbitals. For example, Oxygen has 6 valence electrons (2s² 2p⁴). Transition metals can use d electrons in bonding too.
How do I write the electron configuration of an ion?
For cations (positive ions), remove electrons from the outermost shell first. For example, Fe²⁺ loses two 4s electrons to become [Ar] 3d⁶. For anions (negative ions), add electrons to the outermost shell. Cl⁻ gains one electron to become [Ar], same as Argon.
What is the Aufbau principle?
The Aufbau principle states that electrons fill orbitals from lowest to highest energy. The order is: 1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s → 4d → 5p → 6s → 4f → 5d → 6p → 7s → 5f → 6d → 7p. Notice that 4s fills before 3d because 4s has slightly lower energy.
What do s, p, d, and f mean in electron configuration?
These letters represent orbital shapes (subshells): s orbitals are spherical (max 2 electrons), p orbitals are dumbbell-shaped (max 6 electrons), d orbitals have complex shapes (max 10 electrons), and f orbitals are even more complex (max 14 electrons). The number before indicates the principal energy level (shell).
What is Hund's rule?
Hund's rule states that electrons occupy degenerate (equal energy) orbitals singly before pairing up. Each unpaired electron has the same spin direction. For example, in Nitrogen's 2p³, each of the three 2p orbitals has one electron with parallel spins before any pairing occurs.