Properties of Potassium and Rubidium
Hardness
  
  
Vickers Hardness
Not Available
  
Not Available
  
Optical Properties
  
  
Refractive Index
Not Available
  
Not Available
  
Reflectivity
Not Available
  
Not Available
  
Speed of Sound
2,000.00 m/s
  
99+
1,300.00 m/s
  
99+
Allotropes
No
  
No
  
α Allotropes
Not Available
  
Not Available
  
β Allotropes
Not Available
  
Not Available
  
γ Allotropes
Not Available
  
Not Available
  
Chemical Formula
K
  
Rb
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Sanderson Electronegativity
Allred Rochow Electronegativity
Mulliken-Jaffe Electronegativity
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
418.80 kJ/mol
  
99+
403.00 kJ/mol
  
99+
2nd Energy Level
3,052.00 kJ/mol
  
5
2,633.00 kJ/mol
  
6
3rd Energy Level
4,420.00 kJ/mol
  
8
3,860.00 kJ/mol
  
11
Electrochemical Equivalent
1.46 g/amp-hr
  
99+
3.19 g/amp-hr
  
14
Other Chemical Properties
Density
  
  
Density At Room Temperature
0.86 g/cm3
  
99+
1.53 g/cm3
  
99+
Density When Liquid (at m.p.)
0.83 g/cm3
  
99+
1.46 g/cm3
  
99+
Vapor Pressure
  
  
Vapor Pressure at 1000 K
Not Available
  
Not Available
  
Vapor Pressure at 2000 K
Not Available
  
Not Available
  
Tensile Strength
Not Available
  
Not Available
  
Viscosity
Not Available
  
Not Available
  
Elasticity properties
  
  
Shear Modulus
Not Available
  
Poisson Ratio
Not Available
  
Not Available
  
Other Mechanical Properties
NA
  
Symbol
K
  
Rb
  
Period Number
4
  
5
  
Atomic Volume
45.46 cm3/mol
  
3
55.90 cm3/mol
  
2
Electron Configuration
[Ar] 4s1
  
[Kr] 5s1
  
Valence Electron Potential
10.40 (-eV)
  
99+
9.47 (-eV)
  
99+
Atom
  
  
Crystal Lattice
BCC-Crystal-Structure-.jpg#100
  
BCC-Crystal-Structure-.jpg#100
  
Radius of an Atom
  
  
Lattice Angles
π/2, π/2, π/2
  
π/2, π/2, π/2
  
Lattice C/A Ratio
Not Available
  
Not Available
  
Adjacent Atomic Numbers
  
  
Electrical Properties
  
  
Resistivity
128.00 nΩ·m
  
26
Electrical Conductivity
0.14 106/cm Ω
  
14
0.08 106/cm Ω
  
24
Electron Affinity
48.40 kJ/mol
  
22
46.90 kJ/mol
  
24
Magnetic Characteristics
  
  
Permeability
Not Available
  
Not Available
  
Susceptibility
Not Available
  
Not Available
  
Specific Heat
0.75 J/(kg K)
  
6
0.36 J/(kg K)
  
17
Thermal Conductivity
102.50 W/m·K
  
15
58.20 W/m·K
  
26
Molar Heat Capacity
29.60 J/mol·K
  
6
31.06 J/mol·K
  
5
Thermal Expansion
83.30 µm/(m·K)
  
3
90.00 µm/(m·K)
  
2
Standard Molar Entropy
64.70 J/mol.K
  
18
76.80 J/mol.K
  
5
Enthalpy
  
  
Enthalpy of Vaporization
77.50 kJ/mol
  
99+
69.20 kJ/mol
  
99+
Enthalpy of Fusion
2.32 kJ/mol
  
99+
2.19 kJ/mol
  
99+
Enthalpy of Atomization
89.50 kJ/mol
  
99+
82.00 kJ/mol
  
99+