Ions and the Exceptions
Part of the Atomic Structure section of Coddy's Chemistry journey. Lesson 27 of 45.
An anion gains electrons in the next free places: Cl⁻ is [Ne] 3s² 3p⁶.
A cation loses from the outermost shell first, so 4s empties before 3d: Fe is [Ar] 3d⁶ 4s² and Fe²⁺ is [Ar] 3d⁶.
Fe²⁺
A half-full or full d subshell is extra stable: chromium is [Ar] 3d⁵ 4s¹ and copper is [Ar] 3d¹⁰ 4s¹.
Chromium: [Ar] 3d⁵ 4s¹
Challenge
Iron in your blood carries oxygen as the iron(II) ion, Fe²⁺. Write its electron configuration.
Try it yourself
Electron configurationFill the electrons of Fe2+ (iron)
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Atomic Structure
1Matter and Atoms
What Everything Is Made OfElements, Compounds, MixturesChemical SymbolsCounting Atoms in a FormulaRecap - Molecule Kit4Electron Arrangement
Shells and the First 20Valence ElectronsIonization Energy as EvidenceLight from AtomsSubshells: s, p, dAufbau, Hund and PauliWriting ConfigurationsIons and the ExceptionsRecap - Configuration Race