Francium Rubidium Comparison
Periodic Table
Symbol
Fr
Rb
Group Number
1
17
1
17
Period Number
7
5
Block
s block
s block
Element Family
Alkali
Alkali
CAS Number
7440735
18
7440177
99+
Space Group Name
Not Available
Im_ 3m
Space Group Number
Not Available
229.00
1
Facts
Interesting Facts
- 223 Francium has the longest half life at 21.8.
- Francium metal is produced by alpha decay in 227Actinium 227.
- Rubidium metal is 16th most common element found in the earth crust.
- Rubidium metal also found in minerals as well as seawater.
Sources
Formed by Decay Process, Mining
Obtained from Lithium Production.
History
Who Discovered
Marguerite Perey
Robert Bunsen and Gustav Kirchhoff
Discovery
In 1939
In 1861
Abundance
Abundance In Universe
Not Available
1 * 10-6 %
16
Abundance In Sun
~-9999 %
~0.000003 %
17
Abundance In Meteorites
Not Available
0.00 %
19
Abundance In Earth's Crust
Not Available
0.01 %
18
Abundance In Oceans
Not Available
0.00 %
7
Abundance In Humans
Not Available
0.00 %
7
Uses
Uses & Benefits
- Francium has no known uses as it has a half life of only 22 minutes.
- Rubidium's main application is in the glass manufacturing.
- Rubidium can very easily get ionized and hence it is used for ion engines, but it is still less efficient than that of Caesium.
Industrial Uses
NA
NA
Medical Uses
NA
NA
Other Uses
NA
Alloys, Research Purposes
Biological Properties
Toxicity
NA
Non Toxic
Present in Human Body
No
Yes
In Blood
0.00 Blood/mg dm-3
37
2.49 Blood/mg dm-3
7
In Bone
0.00 p.p.m.
36
5.00 p.p.m.
13
Physical Properties
Melting Point
27.00 °C
99+
38.89 °C
99+
Boiling Point
677.00 °C
99+
688.00 °C
99+
Appearance
Physical State
Solid
Solid
Color
NA
Grayish White
Luster
NA
NA
Hardness
Mohs Hardness
Not Available
0.30
24
Brinell Hardness
Not Available
0.22 MPa
99+
Speed of Sound
Not Available
1,300.00 m/s
99+
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
Fr
Rb
Isotopes
Known Isotopes
33
6
29
10
Electronegativity
Pauling Electronegativity
0.70
99+
0.82
99+
Sanderson Electronegativity
Not Available
0.31
32
Allred Rochow Electronegativity
0.86
99+
0.89
40
Mulliken-Jaffe Electronegativity
0.68
25
0.69
24
Allen Electronegativity
0.67
99+
0.71
99+
Electropositivity
Pauling Electropositivity
3.30
1
3.18
3
Ionization Energies
1st Energy Level
380.00 kJ/mol
99+
403.00 kJ/mol
99+
2nd Energy Level
Not Available
2,633.00 kJ/mol
6
3rd Energy Level
Not Available
3,860.00 kJ/mol
11
4th Energy Level
Not Available
5,080.00 kJ/mol
18
5th Energy Level
Not Available
6,850.00 kJ/mol
19
6th Energy Level
Not Available
8,140.00 kJ/mol
20
7th Energy level
Not Available
9,570.00 kJ/mol
20
8th Energy Level
Not Available
13,120.00 kJ/mol
17
9th Energy Level
Not Available
14,500.00 kJ/mol
18
10th Energy Level
Not Available
26,740.00 kJ/mol
6
Electrochemical Equivalent
8.32 g/amp-hr
1
3.19 g/amp-hr
14
Electron Work Function
Not Available
2.16 eV
99+
Other Chemical Properties
Ionization, Radioactive Isotopes, Radioactivity, Solubility
Corrosion, Ionization, Radioactive Isotopes, Radioactivity
Atomic Properties
Atomic Number
87
31
37
99+
Electron Configuration
[Rn] 7s1
[Kr] 5s1
Crystal Structure
Body Centered Cubic (BCC)
Body Centered Cubic (BCC)
Crystal Lattice
BCC-Crystal-Structure-.jpg#100
BCC-Crystal-Structure-.jpg#100
Atom
Number of Protons
87
31
37
99+
Number of Neutrons
136
17
48
99+
Number of Electrons
87
31
37
99+
Radius of an Atom
Atomic Radius
Not Available
248.00 pm
2
Covalent Radius
260.00 pm
1
220.00 pm
4
Van der Waals Radius
348.00 pm
1
303.00 pm
3
Atomic Weight
223.00 amu
27
85.47 amu
99+
Atomic Volume
Not Available
55.90 cm3/mol
2
Adjacent Atomic Numbers
Valence Electron Potential
8.00 (-eV)
99+
9.47 (-eV)
99+
Lattice Constant
Not Available
558.50 pm
10
Lattice Angles
NA
π/2, π/2, π/2
Lattice C/A Ratio
Not Available
Not Available
Mechanical Properties
Density
Density At Room Temperature
1.87 g/cm3
99+
1.53 g/cm3
99+
Density When Liquid (at m.p.)
Not Available
1.46 g/cm3
99+
Tensile Strength
Not Available
Not Available
Viscosity
Not Available
Not Available
Vapor Pressure
Elasticity properties
Bulk Modulus
Not Available
2.50 GPa
99+
Young's Modulus
Not Available
2.40 GPa
99+
Poisson Ratio
Not Available
Not Available
Other Mechanical Properties
NA
Ductile
Magnetic Properties
Magnetic Characteristics
Specific Gravity
Not Available
1.53
99+
Magnetic Ordering
Paramagnetic
Paramagnetic
Electrical Properties
Electrical Property
Poor Conductor
Conductor
Resistivity
3.00 nΩ·m
99+
128.00 nΩ·m
26
Electrical Conductivity
0.03 106/cm Ω
40
0.08 106/cm Ω
24
Electron Affinity
Not Available
46.90 kJ/mol
24
Thermal Properties
Specific Heat
Not Available
0.36 J/(kg K)
17
Molar Heat Capacity
Not Available
31.06 J/mol·K
5
Thermal Conductivity
15.00 W/m·K
99+
58.20 W/m·K
26
Critical Temperature
Not Available
2,093.00 K
4
Thermal Expansion
Not Available
90.00 µm/(m·K)
2
Enthalpy
Enthalpy of Vaporization
Not Available
69.20 kJ/mol
99+
Enthalpy of Fusion
Not Available
2.19 kJ/mol
99+
Enthalpy of Atomization
71.00 kJ/mol
99+
82.00 kJ/mol
99+
Standard Molar Entropy
Not Available
76.80 J/mol.K
5
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