Lanthanum

57
La
Group
n/a
Period
6
Block
f
Protons
Electrons
Neutrons
57
57
82
General Properties
Atomic Number
57
Atomic Weight
138.90547
Mass Number
139
Category
Lanthanides
Colour
Silver
Radioactive
No
From the Greek word lanthanein, to lie hidden
Crystal Structure
Simple Hexagonal
History
Lanthanum was discovered in 1839 by Swedish chemist Carl Gustav Mosander.

He partially decomposed a sample of cerium nitrate by heating and treating the resulting salt with dilute nitric acid.

From the resulting solution, he obtained a pale brick coloured oxide of the new rare earth.

Lanthanum was isolated in relatively pure form in 1923.
Electrons per shell
2, 8, 18, 18, 9, 2
Electron Configuration
[Xe] 5d1 6s2
La
Lanthanum is the most reactive of the rare earth metals
Physical Properties
Phase
Solid
Density
6.145 g/cm3
Melting Point
1193.15 K | 920 °C | 1688 °F
Boiling Point
3737.15 K | 3464 °C | 6267.2 °F
Heat of Fusion
6.2 kJ/mol
Heat of Vaporization
400 kJ/mol
Specific Heat Capacity
0.195 J/g·K
Abundance in Earth's crust
0.0034%
Abundance in Universe
2×10-7%
Pure
Image Credits: Images-of-elements
Pure lanthanum
CAS Number
7439-91-0
PubChem CID Number
23926
Atomic Properties
Atomic Radius
187 pm
Covalent Radius
207 pm
Electronegativity
1.1 (Pauling scale)
Ionization Potential
5.5769 eV
Atomic Volume
22.5 cm3/mol
Thermal Conductivity
0.135 W/cm·K
Oxidation States
2, 3
Applications
Lanthanum is used in large quantities in batteries for hybrid automobiles.

It is also used to make night vision goggles.

Small amounts of lanthanum, as an additive, can be used to produce nodular cast iron.

Lanthanum carbonate is used to reduce blood levels of phosphate in patients with kidney disease.
Lanthanum and its compounds are considered to be moderately toxic
Isotopes
Stable Isotopes
139La
Unstable Isotopes
117La, 118La, 119La, 120La, 121La, 122La, 123La, 124La, 125La, 126La, 127La, 128La, 129La, 130La, 131La, 132La, 133La, 134La, 135La, 136La, 137La, 138La, 140La, 141La, 142La, 143La, 144La, 145La, 146La, 147La, 148La, 149La, 150La, 151La, 152La, 153La, 154La, 155La