Electron configuration shows how an atom’s electrons are arranged among its orbitals. That arrangement helps explain chemical behavior, bonding, periodic trends, and likely ion formation. Select an element to see its ground-state configuration in compact noble-gas notation.
How to Calculate Electron Configuration (step by step)
Step One: Identify the electron count
For a neutral atom, the atomic number is equal to the number of electrons. The selected element supplies that number directly.
Electrons in a neutral atom = atomic number
For chlorine, the selected atomic number is seventeen.
Electrons = 17
Step Two: Fill orbitals in energy order
Electrons occupy lower-energy orbitals before higher-energy orbitals. The usual sequence begins with 1s, 2s, 2p, 3s, 3p, 4s, and 3d. Each orbital type has a maximum capacity: s holds two electrons, p holds six, and d holds ten.
Fill orbitals from lower energy to higher energy
For chlorine, the first ten electrons are represented by the neon core, then the remaining electrons enter the third shell.
[Ne] + 3s² + 3p⁵
Step Three: Write noble-gas shorthand
Replace the completed inner configuration with the symbol of the preceding noble gas. This keeps the notation readable while preserving the full electron count.
Electron configuration = noble-gas core + remaining occupied orbitals
The calculator’s default example is chlorine.
Chlorine = [Ne] 3s² 3p⁵
What your results mean
The bracketed symbol represents a stable inner electron configuration. The orbitals written after it describe the outer electrons, which are especially important for chemical reactions. Chlorine’s five electrons in the 3p subshell leave it one electron short of the argon arrangement, helping explain why chlorine commonly forms a one-electron anion.
The notation also reveals the element’s position in the periodic table. A configuration ending in p identifies a p-block element, while a configuration containing d electrons identifies a transition element. For a broader reference, compare the result with the science calculator collection and use a molar mass calculator when connecting electron structure to chemical formulas.
This tool reports neutral-atom ground states through krypton. Excited states, transition-metal ions, and heavier atoms can require additional rules, especially when electrons are removed from the 4s subshell before the 3d subshell.