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Lanthanum vs Promethium


Promethium vs Lanthanum


Periodic Table

Symbol
La   
Pm   

Group Number
Not Available   
Not Available   

Period Number
6   
6   

Block
f block   
f block   

Element Family
Lanthanide   
Lanthanide   

CAS Number
7439910   
99+
7440122   
99+

Space Group Name
P63/mmc   
Not Available   

Space Group Number
194.00   
5
Not Available   

Facts

Interesting Facts
  • Lanthanum metal is highly malleable, ductile and sectile.
  • If exposed to air Lanthanum metal oxidizes rapidly.
  
  • Promethium metal found in Pitchblende.
  • Promethium metal is highly radioactive metal.
  

Sources
Found in Minerals, Mining, Ores of Minerals   
Found in Minerals, Mining   

History
  
  

Who Discovered
Carl Gustaf Mosander   
Chien Shiung Wu, Emilio Segrè, Hans Bethe   

Discovery
In 1838   
In 1942   

Abundance
  
  

Abundance In Universe
2 * 10-7 %   
22
Not Available   

Abundance In Sun
~0.0000002 %   
25
~-9999 %   

Abundance In Meteorites
0.00 %   
32
Not Available   

Abundance In Earth's Crust
0.00 %   
19
Not Available   

Abundance In Oceans
0.00 %   
29
Not Available   

Uses

Uses & Benefits
  • It has no commercial uses, but its alloys are in high demand. Lanthanum and Nickel alloy is used for the hydrogen gas storage.
  • The best-known use for mischmetal alloy of Lanthanum is; as a ‘flints’ for cigarette lighters.
  
  • It is used for research purpose. Very small amount of this metal is used in atomic batteries.
  • Its radioactive decay is used for a phosphor to give off light. The light emitted is converted into electricity.
  

Industrial Uses
Electrical Industry, Electronic Industry   
NA   

Medical Uses
NA   
NA   

Other Uses
Alloys, Mirror Manufacturing   
NA   

Biological Properties
  
  

Toxicity
Low Toxic   
Non Toxic   

Present in Human Body
Yes   
No   

In Blood
Not Available   
0.00 Blood/mg dm-3   
37

In Bone
0.08 p.p.m.   
24
Not Available   

Physical Properties

Melting Point
920.00 °C   
99+
1,042.00 °C   
99+

Boiling Point
3,469.00 °C   
18
3,000.00 °C   
31

Appearance
  
  

Physical State
Solid   
Solid   

Color
Silvery White   
Unknown   

Luster
NA   
Metallic   

Hardness
  
  

Mohs Hardness
2.50   
14
Not Available   

Brinell Hardness
350.00 MPa   
30
Not Available   

Vickers Hardness
360.00 MPa   
26
Not Available   

Speed of Sound
2,475.00 m/s   
37
Not Available   

Optical Properties
  
  

Allotropes
No   
No   

α Allotropes
Not Available   
Not Available   

β Allotropes
Not Available   
Not Available   

γ Allotropes
Not Available   
Not Available   

Chemical Properties

Chemical Formula
La   
Pm   

Isotopes
  
  

Known Isotopes
31   
8
27   
12

Electronegativity
  
  

Pauling Electronegativity
1.10   
99+
Not Available   

Allred Rochow Electronegativity
1.08   
31
1.07   
32

Electropositivity
  
  

Pauling Electropositivity
2.90   
10
Not Available   

Ionization Energies
  
  

1st Energy Level
538.10 kJ/mol   
99+
540.00 kJ/mol   
99+

2nd Energy Level
1,067.00 kJ/mol   
99+
1,050.00 kJ/mol   
99+

3rd Energy Level
1,850.30 kJ/mol   
99+
2,150.00 kJ/mol   
99+

4th Energy Level
4,819.00 kJ/mol   
22
3,970.00 kJ/mol   
38

5th Energy Level
5,940.00 kJ/mol   
25
Not Available   

Electrochemical Equivalent
1.73 g/amp-hr   
99+
1.80 g/amp-hr   
36

Electron Work Function
3.50 eV   
31
Not Available   

Other Chemical Properties
Ionization, Radioactive Isotopes, Solubility   
Ionization, Radioactive Isotopes, Solubility   

Atomic Properties

Atomic Number
57   
99+
61   
99+

Electron Configuration
[Xe] 5d2 6s2   
[Xe] 4f5 6s2   

Crystal Structure
Double Hexagonal Close Packed (DHCP)   
Double Hexagonal Close Packed (DHCP)   

Crystal Lattice
DHCP-Crystal-Structure-of-Lanthanum.jpg#100   
DHCP-Crystal-Structure-of-Promethium.jpg#100   

Atom
  
  

Number of Protons
57   
99+
61   
99+

Number of Neutrons
82   
99+
84   
40

Number of Electrons
57   
99+
61   
99+

Radius of an Atom
  
  

Atomic Radius
187.00 pm   
8
183.00 pm   
10

Covalent Radius
207.00 pm   
6
199.00 pm   
12

Van der Waals Radius
240.00 pm   
13
236.00 pm   
16

Atomic Weight
138.91 amu   
99+
145.00 amu   
99+

Atomic Volume
20.73 cm3/mol   
16
22.39 cm3/mol   
12

Adjacent Atomic Numbers
  
  

Previous Element
Barium
  
Neodymium
  

Next Element
Cerium
  
Samarium
  

Valence Electron Potential
40.71 (-eV)   
99+
44.10 (-eV)   
39

Lattice Constant
377.20 pm   
28
Not Available   

Lattice Angles
π/2, π/2, 2 π/3   
Unknown   

Lattice C/A Ratio
1.62   
2
Not Available   

Mechanical Properties

Density
  
  

Density At Room Temperature
6.16 g/cm3   
99+
7.26 g/cm3   
99+

Density When Liquid (at m.p.)
5.94 g/cm3   
99+
Not Available   

Tensile Strength
Not Available   
Not Available   

Viscosity
Not Available   
Not Available   

Vapor Pressure
  
  

Vapor Pressure at 2000 K
0.98 (Pa)   
15
Not Available   

Elasticity properties
  
  

Shear Modulus
14.30 GPa   
40
18.00 GPa   
36

Bulk Modulus
27.90 GPa   
99+
33.00 GPa   
36

Young's Modulus
36.60 GPa   
99+
46.00 GPa   
38

Poisson Ratio
0.28   
17
0.28   
17

Other Mechanical Properties
Ductile   
NA   

Magnetic Properties

Magnetic Characteristics
  
  

Specific Gravity
6.17   
99+
7.26   
99+

Magnetic Ordering
Paramagnetic   
Paramagnetic   

Electrical Properties
  
  

Electrical Property
Conductor   
Conductor   

Resistivity
615.00 nΩ·m   
7
0.75 nΩ·m   
99+

Electrical Conductivity
0.01 106/cm Ω   
99+
Not Available   

Electron Affinity
48.00 kJ/mol   
23
50.00 kJ/mol   
21

Thermal Properties

Specific Heat
0.19 J/(kg K)   
32
0.18 J/(kg K)   
33

Molar Heat Capacity
27.11 J/mol·K   
21
Not Available   

Thermal Conductivity
13.40 W/m·K   
99+
17.90 W/m·K   
99+

Critical Temperature
Not Available   
Not Available   

Thermal Expansion
12.10 µm/(m·K)   
32
9.00 µm/(m·K)   
99+

Enthalpy
  
  

Enthalpy of Vaporization
399.60 kJ/mol   
17
Not Available   

Enthalpy of Fusion
6.20 kJ/mol   
99+
7.50 kJ/mol   
99+

Enthalpy of Atomization
431.00 kJ/mol   
16
310.00 kJ/mol   
34

Standard Molar Entropy
56.90 J/mol.K   
23
Not Available   

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