Symbol
Sr
  
Rb
  
Period Number
5
  
5
  
Block
s block
  
s block
  
Element Family
Alkaline Earth
  
Alkali
  
Space Group Name
Fm_ 3m
  
Im_ 3m
  
Interesting Facts
- Strontium element is softer than Calcium.
- Silvery Strontium turns yellow, if exposed to air.
  
- Rubidium metal is 16th most common element found in the earth crust.
- Rubidium metal also found in minerals as well as seawater.
  
Sources
Found in Minerals, Mining, Ores of Minerals
  
Obtained from Lithium Production.
  
History
  
  
Who Discovered
William Cruickshank
  
Robert Bunsen and Gustav Kirchhoff
  
Discovery
In 1787
  
In 1861
  
Abundance
  
  
Abundance In Sun
~0.000005 %
  
15
~0.000003 %
  
17
Abundance In Earth's Crust
Uses & Benefits
- Strontium metal is used to producing ferrite magnets as well as refining zinc.
-
By-product of nuclear reactors called Strontium-90 is a radioactive isotope; it is absorbed by tissues and destroys bone marrow and cancer growth.
  
- 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
Ammunition Industry, Chemical Industry
  
NA
  
Medical Uses
NA
  
NA
  
Other Uses
Alloys
  
Alloys, Research Purposes
  
Biological Properties
  
  
Toxicity
Non Toxic
  
Non Toxic
  
Present in Human Body
Yes
  
Yes
  
In Blood
0.03 Blood/mg dm-3
  
19
2.49 Blood/mg dm-3
  
7
In Bone
140.00 p.p.m.
  
7
5.00 p.p.m.
  
13
Boiling Point
1,384.00 °C
  
99+
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Silvery White
  
Grayish White
  
Luster
Metallic
  
NA
  
Hardness
  
  
Brinell Hardness
Not Available
  
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 Formula
Sr
  
Rb
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Sanderson Electronegativity
Allred Rochow Electronegativity
Mulliken-Jaffe Electronegativity
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
549.50 kJ/mol
  
99+
403.00 kJ/mol
  
99+
2nd Energy Level
1,064.20 kJ/mol
  
99+
2,633.00 kJ/mol
  
6
3rd Energy Level
4,138.00 kJ/mol
  
10
3,860.00 kJ/mol
  
11
4th Energy Level
5,500.00 kJ/mol
  
13
5,080.00 kJ/mol
  
18
5th Energy Level
6,910.00 kJ/mol
  
18
6,850.00 kJ/mol
  
19
6th Energy Level
8,760.00 kJ/mol
  
18
8,140.00 kJ/mol
  
20
7th Energy level
10,230.00 kJ/mol
  
19
9,570.00 kJ/mol
  
20
8th Energy Level
11,800.00 kJ/mol
  
19
13,120.00 kJ/mol
  
17
9th Energy Level
15,600.00 kJ/mol
  
17
14,500.00 kJ/mol
  
18
10th Energy Level
17,100.00 kJ/mol
  
19
26,740.00 kJ/mol
  
6
11th Energy Level
31,270.00 kJ/mol
  
6
Not Available
  
Electrochemical Equivalent
1.64 g/amp-hr
  
99+
3.19 g/amp-hr
  
14
Other Chemical Properties
Ionization, Radioactive Isotopes, Radioactivity, Solubility
  
Corrosion, Ionization, Radioactive Isotopes, Radioactivity
  
Electron Configuration
[Kr] 5s2
  
[Kr] 5s1
  
Crystal Structure
Face Centered Cubic (FCC)
  
Body Centered Cubic (BCC)
  
Crystal Lattice
FCC-Crystal-Structure-of-Strontium.jpg#100
  
BCC-Crystal-Structure-.jpg#100
  
Atom
  
  
Radius of an Atom
  
  
Atomic Volume
33.70 cm3/mol
  
6
55.90 cm3/mol
  
2
Adjacent Atomic Numbers
  
  
Valence Electron Potential
25.70 (-eV)
  
99+
9.47 (-eV)
  
99+
Lattice Angles
π/2, π/2, π/2
  
π/2, π/2, π/2
  
Lattice C/A Ratio
Not Available
  
Not Available
  
Density
  
  
Density At Room Temperature
2.64 g/cm3
  
99+
1.53 g/cm3
  
99+
Density When Liquid (at m.p.)
2.38 g/cm3
  
99+
1.46 g/cm3
  
99+
Tensile Strength
Not Available
  
Not Available
  
Viscosity
Not Available
  
Not Available
  
Vapor Pressure
  
  
Vapor Pressure at 1000 K
Not Available
  
Elasticity properties
  
  
Shear Modulus
Not Available
  
Bulk Modulus
Not Available
  
Poisson Ratio
Not Available
  
Other Mechanical Properties
NA
  
Ductile
  
Magnetic Characteristics
  
  
Magnetic Ordering
Paramagnetic
  
Paramagnetic
  
Electrical Properties
  
  
Electrical Property
NA
  
Conductor
  
Resistivity
132.00 nΩ·m
  
24
128.00 nΩ·m
  
26
Electrical Conductivity
0.08 106/cm Ω
  
26
0.08 106/cm Ω
  
24
Electron Affinity
5.03 kJ/mol
  
38
46.90 kJ/mol
  
24
Specific Heat
0.30 J/(kg K)
  
18
0.36 J/(kg K)
  
17
Molar Heat Capacity
26.40 J/mol·K
  
28
31.06 J/mol·K
  
5
Thermal Conductivity
35.40 W/m·K
  
37
58.20 W/m·K
  
26
Critical Temperature
Not Available
  
Thermal Expansion
22.50 µm/(m·K)
  
18
90.00 µm/(m·K)
  
2
Enthalpy
  
  
Enthalpy of Vaporization
150.00 kJ/mol
  
99+
69.20 kJ/mol
  
99+
Enthalpy of Fusion
9.16 kJ/mol
  
38
2.19 kJ/mol
  
99+
Enthalpy of Atomization
163.20 kJ/mol
  
99+
82.00 kJ/mol
  
99+
Standard Molar Entropy
55.00 J/mol.K
  
26
76.80 J/mol.K
  
5