Electron Configuration Tool
Instantly generate orbital diagrams and electron configurations. Includes support for noble gas notation and handling of exceptions (like Copper and Chromium).
Ready to Calculate
Select an element or enter an atomic number to view its full electron configuration.
Mastering Electron Configuration
The map of an atom's electrons and their energy levels.
Electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. Knowledge of the electron configuration of different atoms is useful in understanding the structure of the periodic table of elements and for describing the chemical bonds that hold atoms together.
The Rules of the Game
- 1Aufbau Principle: Electrons fill the lowest energy orbitals first (1s before 2s).
- 2Pauli Exclusion Principle: No two electrons can have the same four quantum numbers. An orbital can hold max 2 electrons with opposite spins.
- 3Hund's Rule: For degenerate orbitals (like p, d, f), electrons fill each orbital singly before pairing up.
Standard Filling Order
Note: This order minimizes energy, but exceptions exist (e.g., Cr, Cu) due to stability of half-filled subshells.
Real-World Applications
Laser Technology
Lasers (like Neon lights) work by exciting electrons to higher orbitals. When they fall back to stable configurations, they emit light of specific colors.
Spectroscopy
Astronomers identify elements in distant stars by analyzing the light spectra emitted by electron transitions, which are unique fingerprints for each element.
Chemical Bonding
Valence electrons determine how atoms bond. Understanding configuration explains why Salt (NaCl) forms or why Carbon creates organic life.
Frequently Asked Questions
What is Noble Gas Notation?
Noble gas notation is a shorthand method where the core electrons are replaced by the symbol of the nearest noble gas with a lower atomic number in brackets. For example, Calcium (20) is written as [Ar] 4s² instead of 1s² 2s² 2p⁶ 3s² 3p⁶ 4s².
Why do Chromium and Copper have exceptional configurations?
Chromium (Cr, Z=24) is [Ar] 4s¹ 3d⁵ instead of 4s² 3d⁴ because a half-filled d-subshell offers extra stability. Similarly, Copper (Cu, Z=29) is [Ar] 4s¹ 3d¹⁰ to achieve a fully filled d-subshell, which is more stable than 4s² 3d⁹.
What are valence electrons?
Valence electrons are the electrons in the outermost shell (highest principal quantum number, n) of an atom. These electrons are involved in chemical bonding and reactions. For main group elements, the number of valence electrons equals the group number (1-8).
How do I find the number of neutrons?
Electron configuration only deals with electrons (which equal protons in a neutral atom). To find neutrons, you need the isotope's mass number: Neutrons = Mass Number - Atomic Number.
What is the maximum number of electrons in each shell?
The 's' subshell holds 2, 'p' holds 6, 'd' holds 10, and 'f' holds 14. The total capacity of a principal shell (n) is 2n². For example, shell n=3 can hold 2(3²) = 18 electrons.
What is an orbital diagram?
An orbital diagram visually represents electrons as arrows in boxes (orbitals). Up and down arrows indicate opposite spins. It helps visualize Hund's rule and unpaired electrons.
Does this tool support ions?
Currently, this calculator provides configurations for neutral atoms (ground state). For ions (like Na⁺ or Cl⁻), you would subtract or add electrons from the valence shell respectively.
What is the difference between an orbit and an orbital?
An orbit (Bohr model) is a fixed path where an electron travels. An orbital (Quantum model) is a 3D region of space where there is a high probability (90%) of finding an electron.
Why does the 4s orbital fill before the 3d orbital?
According to the Aufbau principle, the 4s orbital has slightly lower energy than the 3d orbital in neutral atoms (except for hydrogen), so it fills first. However, when forming ions, 4s electrons are also removed first.
Can I use this for elements beyond 118?
Elements beyond 118 (Oganesson) are hypothetical and have not been synthesized or observed. The tool supports standard verified elements up to Z=118.