Properties of Lanthanum and Terbium
Melting Point
1,356.00 °C
  
33
Boiling Point
3,469.00 °C
  
18
3,123.00 °C
  
29
Hardness
  
  
Mohs Hardness
Not Available
  
Optical Properties
  
  
Refractive Index
Not Available
  
Not Available
  
Reflectivity
Not Available
  
Not Available
  
Speed of Sound
2,475.00 m/s
  
37
2,620.00 m/s
  
35
Allotropes
No
  
No
  
α Allotropes
Not Available
  
Not Available
  
β Allotropes
Not Available
  
Not Available
  
γ Allotropes
Not Available
  
Not Available
  
Chemical Formula
La
  
Tb
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Not Available
  
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
Not Available
  
Ionization Energies
  
  
1st Energy Level
538.10 kJ/mol
  
99+
603.40 kJ/mol
  
99+
2nd Energy Level
1,067.00 kJ/mol
  
99+
1,174.80 kJ/mol
  
99+
3rd Energy Level
1,850.30 kJ/mol
  
99+
2,417.00 kJ/mol
  
99+
Electrochemical Equivalent
1.73 g/amp-hr
  
99+
1.98 g/amp-hr
  
31
Other Chemical Properties
Density
  
  
Density At Room Temperature
6.16 g/cm3
  
99+
8.23 g/cm3
  
99+
Density When Liquid (at m.p.)
5.94 g/cm3
  
99+
Vapor Pressure
  
  
Vapor Pressure at 1000 K
Not Available
  
Tensile Strength
Not Available
  
Viscosity
Not Available
  
Not Available
  
Elasticity properties
  
  
Other Mechanical Properties
Symbol
La
  
Tb
  
Group Number
Not Available
  
Not Available
  
Period Number
6
  
6
  
Atomic Weight
138.91 amu
  
99+
158.93 amu
  
99+
Atomic Volume
20.73 cm3/mol
  
16
19.20 cm3/mol
  
22
Electron Configuration
[Xe] 5d2 6s2
  
[Xe] 4f9 6s2
  
Valence Electron Potential
40.71 (-eV)
  
99+
46.80 (-eV)
  
33
Atom
  
  
Crystal Lattice
DHCP-Crystal-Structure-of-Lanthanum.jpg#100
  
HCP-Crystal-Structure-of-Terbium.jpg#100
  
Radius of an Atom
  
  
Lattice Angles
π/2, π/2, 2 π/3
  
π/2, π/2, 2 π/3
  
Adjacent Atomic Numbers
  
  
Electrical Properties
  
  
Electrical Conductivity
0.01 106/cm Ω
  
99+
0.01 106/cm Ω
  
99+
Electron Affinity
48.00 kJ/mol
  
23
50.00 kJ/mol
  
21
Magnetic Characteristics
  
  
Permeability
Not Available
  
Not Available
  
Susceptibility
Not Available
  
Not Available
  
Specific Heat
0.19 J/(kg K)
  
32
0.18 J/(kg K)
  
33
Thermal Conductivity
13.40 W/m·K
  
99+
11.10 W/m·K
  
99+
Critical Temperature
Not Available
  
Not Available
  
Molar Heat Capacity
27.11 J/mol·K
  
21
28.91 J/mol·K
  
9
Thermal Expansion
12.10 µm/(m·K)
  
32
10.30 µm/(m·K)
  
38
Standard Molar Entropy
56.90 J/mol.K
  
23
73.20 J/mol.K
  
10
Enthalpy
  
  
Enthalpy of Vaporization
399.60 kJ/mol
  
17
330.90 kJ/mol
  
26
Enthalpy of Fusion
6.20 kJ/mol
  
99+
10.80 kJ/mol
  
34
Enthalpy of Atomization
431.00 kJ/mol
  
16
314.00 kJ/mol
  
33