57 - Lanthanum lanthanide

Discovered by Carl Gustaf Mosander in 1839

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Lanthanum

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.

Periodic table

 Shell Electrons Orbitals
122 in 1s
282 in 2s + 6 in 2p
3182 in 3s + 6 in 3p + 10 in 3d
4182 in 4s + 6 in 4p + 10 in 4d
592 in 5s + 6 in 5p + 1 in 5d
622 in 6s

Electron shells

silvery white Appearance
139  u Atomic Mass
1.95  Å Atomic Radius
3.74k  K Boiling Point
3 Group
3 Common Oxidation States
2.07  Å Covalent Radius
6.16  g/cm³ Density
53  kJ/mol Electron Affinity
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 5d1 Electron Configuration
[Xe] 5d16s2 Electron Configuration (semantic)
1.1 Electronegativity
57 Electrons
5.58  eV First Ionization Energy
2, 3 ICSD Oxidation States
538.1, 1067, 1850.3, 4819, 5940  kJ/mol Ionization Energies
1.19k  K Melting Point
33 Mendeleev Number
27.1  J/(mol·K) Molar Heat
6 Number of Shells
82 Neutrons
57 Atomic Number
19 Number of Isotopes
2, 3 Oxidation States
6 Period
Solid Phase
57 Protons
2, 8, 18, 18, 9, 2 Electron Shell Occupations