Periodic Table of the Elements
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Bottom FACULTY OF CHEMICAL TECHNOLOGY o PERIODIC TABLE OF THE ELEMENTS Bottom
  A B C D E F G H I J K L M N O P R S T U V X Z  
Periodic Table of the Elements Tableau périodique des éléments Periodni sustav elemenata Tavola periodica degli elementi Das Periodensystem der Elemente
Lanthanum Lanthane Lantan Lantanio Lanthan

 
Atomic number: 57
Group numbers: 3
Period: 6
 
Discovery date: 1839
La

Lanthanum
NEIGHBOURS
38
Sr
 39
Y
 
56
Ba
 57
La
 58
Ce
88
Ra
 89
Ac
 90
Th


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Lanthanum was discovered by Carl Gustaf Mosander (Sweden) in 1839. The origin of the name comes from the Greek word lanthanein meaning to lie hidden. It is soft, silvery-white, malleable, ductile metal. Readily tarnishes in air. Reaction with water releases hydrogen gas. Metal ignites and burns readily. Reacts with oxidants.
Bottom TRANSITION ELEMENT: SCANDIUM GROUP Top

Relative atomic mass: 138.9055(2) Electronic configuration: [Xe] 5d1 6s2
Formal oxidation number: +3 Electronegativities: 1.1
Thermal conductivity: 13.5 W m-1 K-1 Electrical resistivity (20 °C): 57 μΩcm
Atomic radius: 187 pm Standard state (20 °C): solid
Density (g dm-3): 6145 (298 K) Molar volume (cm3 mol-1): 22.60 (298 K)


Bottom THERMAL PROPERTIES Top

Melting point: 918 °C Heat of fusion: 10.04 kJ mol-1
Boiling point: 3464 °C Heat of vaporization: 402.1 kJ mol-1
Critical temperature: 10227 °C Heat of atomization: 431.29 kJ mol-1


Bottom IONIZATION ENERGIES AND ABUNDANCE Top

1st ionization energy: 538.10 kJ mol-1 Abundance of element (air): - ppm
2nd ionization energy: 1067.14 kJ mol-1 Abundance of element (Earth's crust): 16 ppm
3rd ionization energy: 1850.34 kJ mol-1 Abundance of element (oceans): 0.0003 ppm


Bottom ISOTOPES Top

Isotopes Relative atomic mass Abundance (%)
138La137.907107(4)0.0902(2)
139La138.906348(3)99.9098(2)


Bottom MINERALS AND USES Top

Lanthanum is found with rare earths in monazite and bastnasite. Monazite sand typical contains 25% lanthanum. It is used in the electrodes of high-intensity, carbon-arc lights. Because it gives glass refractive properties, it is used in expensive camera lenses. The price of 99.9 % pure lanthanum pieces is 232.50 € for 100 g.

Bottom REDUCTION POTENTIALS Top

Balanced half-reaction   Eo / V      Annotation
La3+ + 3e- = La(s) - 2.52  
La(OH)3(s) + 3e- = La(s) + 3OH- - 2.90  

 

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