Pick an element. See its electrons fill the K-L-M shells, where the valence shell sits, and how close it is to a stable octet.
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Tap any element ↓
Ground-state electron configurations from the CRC Handbook of Chemistry & Physics (104th ed.), NIST Atomic Spectra Database, and IUPAC. Anomalies (Cr, Cu, Pd, Pt, Au, Cm, Lr, …) reflect measured assignments. Elements with Z ≥ 104 use predicted Aufbau configurations.