57 - Lanthanum lanthanide
Discovered by Carl Gustaf Mosander in 1839
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.
H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
57-71 La-Lu Lanthanides
89-103 Ac-Lr Actinides
| Shell | Electrons | Orbitals |
|---|---|---|
| 1 | 2 | 2 in 1s |
| 2 | 8 | 2 in 2s + 6 in 2p |
| 3 | 18 | 2 in 3s + 6 in 3p + 10 in 3d |
| 4 | 18 | 2 in 4s + 6 in 4p + 10 in 4d |
| 5 | 9 | 2 in 5s + 6 in 5p + 1 in 5d |
| 6 | 2 | 2 in 6s |
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