Understanding the scientific rationale behind Lanthanum's position in the periodic table:
Serves as the lead element of the Lanthanides (historically Group 3) filling the 4f/5d energy levels.
Belongs to Period 6 because its valence electrons fill the n=6 shell (6s²).
Electronically a d-block element ([Xe] 5d¹ 6s²), but classified as the first member of the f-block lanthanide series.
Classified as a lanthanide rare earth metal with typical trivalent chemistry (+3).
Hover or tap any shell orbit ring to inspect electron counts and 2n² capacities.
Educational Note: This Niels Bohr planetary model visually illustrates principal quantum energy shells ($n=1, 2, 3\dots$) and electron counts. In modern quantum mechanics (Schrödinger model), electrons do not orbit in fixed circular planetary tracks, but exist as 3D probability clouds (orbitals: $s, p, d, f$) governed by the Heisenberg uncertainty principle.
Neutral ground state configuration. Valence electrons: 3.
Found in rare earth phosphate ores monazite and bastnäsite alongside other light lanthanides.
From Greek 'lanthanein' meaning to lie hidden
Low to moderate toxicity; lanthanum powder is combustible and reacts slowly with cold water to generate hydrogen.