Lanthanum (La), element 57 – Learn Acer periodic table

Lanthanum

Lanthanide, atomic number 57.

Lanthanum is a soft, ductile, silvery-white metallic chemical element with symbol La and atomic number 57. It tarnishes rapidly when exposed to air and is soft enough to be cut with a knife. It gave its name to the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table:it is also sometimes considered the first element of the 6th-period transition metals.

Facts

Symbol La. Atomic mass 138.905477 u. Group 3, period 6. Electron configuration [Xe] 5d1 6s2. Electrons per shell 2, 8, 18, 18, 9, 2. State at room temperature: Solid. Melting point 919.9 °C, boiling point 3463.8 °C. Discovered by Carl Gustaf Mosander.

Element data from Wikipedia, CC BY-SA 3.0.