57 La 138.905477

Lanthanum

LANTHANIDE

Phase: Solid

Discovered: Carl Gustaf Mosander

Block: F

Summary

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.

Appearance: silvery white

Source: Wikipedia

Physical Properties

Atomic Mass 138.905477 u

Density 6.162 g/cm³

Melting Point 1193 K

Boiling Point 3737 K

Molar Heat 27.11 J/(mol·K)

Electron Affinity 53 kJ/mol

Ionization Energies

1^st: 538.1 kJ/mol

2^nd: 1067 kJ/mol

3^rd: 1850.3 kJ/mol

4^th: 4819 kJ/mol

5^th: 5940 kJ/mol