Lanthanum

Lanthanum is a chemical element, having the chemical symbol La.

Lanthanum 138.9055(2)   La 57 [ ? ] Transition metal:

Its atomic number (the number of protons) is 57. It has a Standard Atomic Weight of 138.9055(2), and is typically found as a solid in its elemental form.

Lanthanum is considered to be a member of the "Transition metal" class of elements, has a boiling point of 3,464 °C , and a melting point of 918 °C .

A white, soft element, lanthanum is classified in a number of different "categories" of elements. In addition to being a transition metal, it belongs to the rare earth metals, (which include scandium, yttrium, and actinium), and is also the namesake of the lanthanides, a group of elements in the periodic table having atomic numbers from 57 (lanthinide itself) to 71 (lutetium).