Enter an element symbol or atomic number (1–118) to get the Aufbau electron configuration, orbital box diagram, valence electrons and period/group.
Symbol
Name
Atomic number
Period
Group
Block
Valence electrons
Electrons / shell
Block
Electron configuration
Full (Aufbau)
Noble-gas shorthand
Orbital box diagram
↑unpaired↑↓pairedempty
Enter an element symbol (e.g. Na, Fe, Cu) or atomic number (1–118). Electrons fill orbitals by the Aufbau principle in energy order 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p. Each orbital holds at most 2 electrons (Pauli); within a subshell, electrons occupy separate orbitals first (Hund's rule). A few transition-metal and lanthanide/actinide ground states deviate from the Aufbau prediction for half-filled / fully-filled stability — these are flagged in the note.