Hey future chemist! 🧠 Ready to explore the quirky exceptions to the Aufbau principle? This isn't just about memorizing rules; it's about seeing how atoms like to break the rules sometimes. Strap in, and let's dive into the fascinating world of transition metals and atomic configurations.

• Basics: The Aufbau principle predicts the order in which electrons fill atomic orbitals. Think of it as the "rulebook" for where electrons go in an atom.
• But Wait... Exceptions? Yep, you read that right! There are exceptions to these rules, especially when atoms lose electrons to form ions.

• Electron Configuration: Mn's configuration is [Ar] 4s² 3d⁵.
• The Twist: When Mn loses two electrons to become Mn²⁺, it loses the 4s electrons first. So, its ion is [Ar] 3d⁵, not [Ar] 4s² 3d³.
• Real-World Example: Manganese is used in batteries. The way it loses electrons affects its chemical behavior!

• The 3d Club: Elements with 3d valence electrons (like scandium to copper) often lose two 4s electrons to form 2+ ions.
• Oxidation States: These metals can have variable oxidation states, meaning they play different roles in compounds.