Properties of Samarium and Praseodymium
Melting Point
1,072.00 °C
  
99+
Boiling Point
1,900.00 °C
  
99+
3,130.00 °C
  
27
Hardness
  
  
Mohs Hardness
Not Available
  
Not Available
  
Optical Properties
  
  
Refractive Index
Not Available
  
Not Available
  
Reflectivity
Not Available
  
Not Available
  
Speed of Sound
2,130.00 m/s
  
99+
2,280.00 m/s
  
40
Allotropes
No
  
No
  
α Allotropes
Not Available
  
Not Available
  
β Allotropes
Not Available
  
Not Available
  
γ Allotropes
Not Available
  
Not Available
  
Chemical Formula
Sm
  
Pr
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Sanderson Electronegativity
Not Available
  
Not Available
  
Allred Rochow Electronegativity
Mulliken-Jaffe Electronegativity
Not Available
  
Not Available
  
Allen Electronegativity
Not Available
  
Not Available
  
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
544.50 kJ/mol
  
99+
527.00 kJ/mol
  
99+
2nd Energy Level
1,070.00 kJ/mol
  
99+
1,020.00 kJ/mol
  
99+
3rd Energy Level
2,260.00 kJ/mol
  
99+
2,086.00 kJ/mol
  
99+
Electrochemical Equivalent
1.87 g/amp-hr
  
34
1.75 g/amp-hr
  
40
Other Chemical Properties
Density
  
  
Density At Room Temperature
7.52 g/cm3
  
99+
6.77 g/cm3
  
99+
Density When Liquid (at m.p.)
Vapor Pressure
  
  
Vapor Pressure at 2000 K
Not Available
  
Tensile Strength
Not Available
  
Not Available
  
Viscosity
Not Available
  
Not Available
  
Elasticity properties
  
  
Other Mechanical Properties
NA
  
Symbol
Sm
  
Pr
  
Group Number
Not Available
  
Not Available
  
Period Number
6
  
6
  
Atomic Weight
150.36 amu
  
99+
140.91 amu
  
99+
Atomic Volume
19.95 cm3/mol
  
19
20.80 cm3/mol
  
15
Electron Configuration
[Xe] 4f6 6s2
  
[Xe] 4f3 6s2
  
Valence Electron Potential
44.80 (-eV)
  
37
42.64 (-eV)
  
99+
Atom
  
  
Crystal Lattice
RHO-Crystal-Structure-of-Samarium.jpg#100
  
HCP-Crystal-Structure-of-Praseodymium.jpg#100
  
Radius of an Atom
  
  
Lattice Angles
π/2, π/2, 2 π/3
  
π/2, π/2, 2 π/3
  
Lattice C/A Ratio
Not Available
  
Adjacent Atomic Numbers
  
  
Electrical Properties
  
  
Electrical Conductivity
0.01 106/cm Ω
  
99+
0.01 106/cm Ω
  
99+
Electron Affinity
50.00 kJ/mol
  
21
50.00 kJ/mol
  
21
Magnetic Characteristics
  
  
Permeability
Not Available
  
Not Available
  
Susceptibility
Not Available
  
Not Available
  
Specific Heat
0.20 J/(kg K)
  
31
0.19 J/(kg K)
  
32
Thermal Conductivity
13.30 W/m·K
  
99+
12.50 W/m·K
  
99+
Critical Temperature
Not Available
  
Not Available
  
Molar Heat Capacity
29.54 J/mol·K
  
7
27.20 J/mol·K
  
18
Thermal Expansion
12.70 µm/(m·K)
  
30
6.70 µm/(m·K)
  
99+
Standard Molar Entropy
69.60 J/mol.K
  
15
73.20 J/mol.K
  
10
Enthalpy
  
  
Enthalpy of Vaporization
166.40 kJ/mol
  
99+
296.80 kJ/mol
  
29
Enthalpy of Fusion
8.62 kJ/mol
  
40
6.89 kJ/mol
  
99+
Enthalpy of Atomization
209.00 kJ/mol
  
99+
368.00 kJ/mol
  
24