Generate electron configurations for all 118 elements. Shows orbital filling, noble gas core notation, orbital diagrams, valence electrons, and quantum number sets.
An electron configuration describes how electrons are distributed among the atomic orbitals of an atom. Electrons fill orbitals in order of increasing energy according to the aufbau principle, with each orbital holding at most two electrons (Pauli exclusion principle), and degenerate orbitals being half-filled before any is fully occupied (Hund's rule).
Electron configurations directly determine an element's chemical properties: its position in the periodic table, ionization energy, electron affinity, bonding behavior, and magnetic properties. The configuration also reveals how many valence electrons are available for bonding and whether any are unpaired.
This calculator generates the electron configuration for any element, with options for atomic number, symbol, or ion. It shows the full configuration, noble gas shorthand, orbital box diagrams with electron arrows, valence electron count, and the set of quantum numbers for the last electron added. Common exceptions (Cr, Cu, and others) are handled correctly.
For best results, combine calculator output with direct observation and periodic check-ins with a veterinarian or qualified advisor. Small adjustments made early usually improve comfort, safety, and long-term outcomes more than large corrective changes made later.
Instantly generate correct electron configurations including exceptions. View orbital diagrams, identify unpaired electrons, and determine magnetic properties for any element or ion. This electron configuration calculator helps you compare outcomes quickly and reduce avoidable mistakes when making day-to-day care decisions. Use the estimate as a planning baseline and confirm final decisions with a qualified professional when risk is high.
Aufbau order: 1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s → 4d → 5p → 6s → 4f → 5d → 6p → 7s → 5f → 6d → 7p\n\nSubshell capacity: s=2, p=6, d=10, f=14\nValence electrons = electrons in outermost shell (highest n) This keeps planning practical and lowers the chance of preventable errors.
Result: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶ — [Ar] 4s² 3d⁶
Iron (Z=26) has 26 electrons. After filling through argon's 18 electrons [Ar], the remaining 8 fill: 4s² 3d⁶. Iron has 2 valence electrons (in 4s) and 4 unpaired electrons (in 3d), making it paramagnetic.
Each electron in an atom is described by four quantum numbers: n (1,2,3...), l (0 to n-1), mₗ (-l to +l), and mₛ (+½ or -½). No two electrons can share all four quantum numbers (Pauli exclusion). The aufbau principle and Hund's rule govern the order of filling.
Several elements prefer half-filled or fully filled d and f subshells. Chromium ([Ar] 4s¹ 3d⁵) and copper ([Ar] 4s¹ 3d¹⁰) are the most commonly tested examples. In the f-block, anomalies are even more common because the energy differences between 4f, 5d, and 6s orbitals are very small.
Electron configurations explain periodic trends: elements in the same group share the same valence configuration (e.g., all alkali metals are [noble gas] ns¹). Ionization energies, electron affinities, and electronegativity all correlate with how tightly the outermost electrons are held.
Half-filled subshells (d⁵) are extra stable due to exchange energy. Chromium promotes one 4s electron to achieve this favored configuration, and copper does similarly to get a full d¹⁰.
For cations, remove electrons from the highest principal quantum number first (usually s before d). For Fe²⁺, remove two 4s electrons: [Ar] 3d⁶. For anions, add electrons to the next available orbital.
Electrons in the outermost shell (highest n). Main group: s and p in outer shell. Transition metals: typically count only s electrons as valence, or both s and d for bonding.
n = principal (shell), l = angular momentum (subshell shape: 0=s, 1=p, 2=d, 3=f), mₗ = magnetic (orbital orientation), mₛ = spin (+½ or -½). This keeps planning practical and lowers the chance of preventable errors.
Due to electron-electron repulsion and shielding effects, 4s fills before 3d because its greater penetration near the nucleus gives it lower energy in multi-electron atoms. This keeps planning practical and lowers the chance of preventable errors.
About 20 elements have configurations that differ from strict aufbau predictions, mostly in the d-block (Cr, Cu, Mo, Ag, Au, Pt) and f-block (many lanthanides and actinides). This keeps planning practical and lowers the chance of preventable errors.