Symbol
Co
  
Cr
  
Period Number
4
  
4
  
Block
d block
  
d block
  
Element Family
Transition Metal
  
Transition Metal
  
Space Group Name
P63/mmc
  
Im_ 3m
  
Interesting Facts
- The main source of Cobalt is as a by-product of copper and nickel metal mining.
- Cobalt metal can be obtained from other elements like Oxygen, Sulfur and Arsenic.
- It s also used in electroplating process as it exhibits anti cession properties.
  
- Chromium is highly reactive, hence it is not found free in nature.
- Ores of Chromites mineral are the major source of Chromium metal.
- Almost 90% leather tanning is done with the help of chromium.
  
Sources
Found in Compounds, Mining, Ores of Minerals
  
Found in Minerals, Mining, Ores of metals, Ores of Minerals
  
History
  
  
Who Discovered
Georg Brandt
  
Louis Nicolas Vauquelin
  
Discovery
In 1732
  
In Between 1797 - 1798
  
Abundance
  
  
Abundance In Universe
1.5 * 10-3 %
  
7
Abundance In Earth's Crust
Uses & Benefits
- Its alloys with aluminum and nickel are used to make powerful magnets.
-
Few other alloys exhibit high-temperature strength and hence they are used in Turbines of Jet and Gas engine.
  
- It is used to harden the steel and produces a stainless steel and other various alloys.
- It is also used to give proper finish to polished mirrors. Its chromium plates are used in bathroom fittings.
  
Industrial Uses
Chemical Industry, Electrical Industry, Electronic Industry
  
Automobile Industry, Chemical Industry
  
Medical Uses
Pharmaceutical Industry
  
NA
  
Other Uses
Alloys
  
Alloys
  
Biological Properties
  
  
Toxicity
Toxic
  
Highly Toxic
  
Present in Human Body
Yes
  
Yes
  
In Blood
0.04 Blood/mg dm-3
  
18
0.11 Blood/mg dm-3
  
12
In Bone
0.04 p.p.m.
  
27
0.33 p.p.m.
  
21
Melting Point
1,495.00 °C
  
29
1,857.00 °C
  
14
Boiling Point
2,870.00 °C
  
34
2,672.00 °C
  
39
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Gray
  
Silver
  
Luster
Metallic
  
Metallic
  
Hardness
  
  
Vickers Hardness
1,043.00 MPa
  
11
1,060.00 MPa
  
10
Speed of Sound
4,720.00 m/s
  
14
5,940.00 m/s
  
5
Optical Properties
  
  
Reflectivity
Not Available
  
Allotropes
Yes
  
No
  
α Allotropes
α-Cobalt
  
Not Available
  
β Allotropes
β-Cobalt
  
Not Available
  
γ Allotropes
Not Available
  
Not Available
  
Chemical Formula
Co
  
Cr
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Sanderson Electronegativity
Allred Rochow Electronegativity
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
760.40 kJ/mol
  
19
26,130.00 kJ/mol
  
1
2nd Energy Level
1,648.00 kJ/mol
  
31
28,750.00 kJ/mol
  
1
3rd Energy Level
3,232.00 kJ/mol
  
22
34,230.00 kJ/mol
  
1
4th Energy Level
4,950.00 kJ/mol
  
19
37,066.00 kJ/mol
  
1
5th Energy Level
7,670.00 kJ/mol
  
12
97,510.00 kJ/mol
  
1
6th Energy Level
9,840.00 kJ/mol
  
12
105,800.00 kJ/mol
  
1
7th Energy level
12,440.00 kJ/mol
  
11
114,300.00 kJ/mol
  
1
8th Energy Level
15,230.00 kJ/mol
  
12
125,300.00 kJ/mol
  
1
9th Energy Level
17,959.00 kJ/mol
  
13
134,700.00 kJ/mol
  
1
10th Energy Level
26,570.00 kJ/mol
  
7
144,300.00 kJ/mol
  
1
11th Energy Level
29,400.00 kJ/mol
  
8
26,130.00 kJ/mol
  
12
12th Energy Level
32,400.00 kJ/mol
  
8
28,750.00 kJ/mol
  
13
13th Energy Level
36,600.00 kJ/mol
  
8
34,230.00 kJ/mol
  
10
14th Energy Level
39,700.00 kJ/mol
  
9
37,066.00 kJ/mol
  
12
15th Energy Level
42,800.00 kJ/mol
  
12
97,510.00 kJ/mol
  
1
16th Energy Level
49,396.00 kJ/mol
  
11
105,800.00 kJ/mol
  
2
17th Energy Level
52,737.00 kJ/mol
  
13
114,300.00 kJ/mol
  
3
18th Energy Level
134,810.00 kJ/mol
  
1
125,300.00 kJ/mol
  
4
19th Energy Level
145,170.00 kJ/mol
  
2
134,700.00 kJ/mol
  
5
20th Energy Level
154,700.00 kJ/mol
  
4
144,300.00 kJ/mol
  
7
21st Energy Level
167,400.00 kJ/mol
  
4
157,700.00 kJ/mol
  
7
22nd Energy Level
178,100.00 kJ/mol
  
3
166,090.00 kJ/mol
  
6
23rd Energy Level
189,300.00 kJ/mol
  
3
Not Available
  
Electrochemical Equivalent
1.10 g/amp-hr
  
99+
0.32 g/amp-hr
  
99+
Other Chemical Properties
Chemical Stability, Ionization
  
Anti Corrosion, Chemical Stability, Ionization, Radioactive Isotopes, Solubility
  
Electron Configuration
[Ar] 3d2 4s2
  
[Ar] 3d5 4s1
  
Crystal Structure
Hexagonal Close Packed (HCP)
  
Body Centered Cubic (BCC)
  
Crystal Lattice
HCP-Crystal-Structure-of-Cobalt.jpg#100
  
BCC-Crystal-Structure-.jpg#100
  
Atom
  
  
Radius of an Atom
  
  
Atomic Volume
10.64 cm3/mol
  
99+
7.23 cm3/mol
  
99+
Adjacent Atomic Numbers
  
  
Valence Electron Potential
95.20 (-eV)
  
10
170.00 (-eV)
  
4
Lattice Angles
π/2, π/2, 2 π/3
  
π/2, π/2, π/2
  
Lattice C/A Ratio
Not Available
  
Not Available
  
Density
  
  
Density At Room Temperature
4.51 g/cm3
  
99+
7.19 g/cm3
  
99+
Density When Liquid (at m.p.)
4.11 g/cm3
  
99+
Viscosity
Not Available
  
Not Available
  
Vapor Pressure
  
  
Vapor Pressure at 1000 K
Not Available
  
Elasticity properties
  
  
Other Mechanical Properties
Ductile
  
NA
  
Magnetic Characteristics
  
  
Magnetic Ordering
Paramagnetic
  
Antiferromagnetic
  
Electrical Properties
  
  
Electrical Property
Poor Conductor
  
NA
  
Resistivity
420.00 nΩ·m
  
12
125.00 nΩ·m
  
27
Electrical Conductivity
0.02 106/cm Ω
  
99+
0.08 106/cm Ω
  
25
Electron Affinity
7.60 kJ/mol
  
37
64.30 kJ/mol
  
15
Specific Heat
0.52 J/(kg K)
  
9
0.45 J/(kg K)
  
12
Molar Heat Capacity
25.06 J/mol·K
  
99+
23.35 J/mol·K
  
99+
Thermal Conductivity
21.90 W/m·K
  
99+
93.90 W/m·K
  
17
Critical Temperature
Not Available
  
Not Available
  
Thermal Expansion
8.60 µm/(m·K)
  
99+
4.90 µm/(m·K)
  
99+
Enthalpy
  
  
Enthalpy of Vaporization
429.00 kJ/mol
  
15
348.80 kJ/mol
  
24
Enthalpy of Fusion
15.48 kJ/mol
  
19
15.31 kJ/mol
  
20
Enthalpy of Atomization
468.60 kJ/mol
  
15
397.50 kJ/mol
  
21
Standard Molar Entropy
27.30 J/mol.K
  
99+
23.80 J/mol.K
  
99+