- Atomic Radius (Å)
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.
57
Atomic Number
138.91 u
Atomic Mass
1193.15 K
Melting Point
3737 K
Boiling Point
6.16 g/cm³
Density
2.7 Å
Atomic Radius
2.07 Å
Covalent Radius
1.1
Electronegativity
5.58 eV
First Ionization Energy
53
Electron Affinity
6
Number of Shells
2, 8, 18, 18, 9, 2
Electron Shell Occupations
0.2 J/g
Specific Heat