Cobalt vs Chromium
Periodic Table
Symbol
Co
Cr
Group Number
9
9
6
12
Period Number
4
4
Block
d block
d block
Element Family
Transition Metal
Transition Metal
CAS Number
7440484
38
7440473
39
Space Group Name
P63/mmc
Im_ 3m
Space Group Number
194.00
5
229.00
1
Facts
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
3 * 10-4 %
9
1.5 * 10-3 %
7
Abundance In Sun
~0.0004 %
9
~0.002 %
7
Abundance In Meteorites
0.06 %
10
0.30 %
7
Abundance In Earth's Crust
0.00 %
21
0.01 %
13
Abundance In Oceans
0.00 %
20
0.00 %
16
Abundance In Humans
0.00 %
17
0.00 %
16
Uses
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
Physical Properties
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
Mohs Hardness
5.00
8
8.50
1
Brinell Hardness
470.00 MPa
26
687.00 MPa
16
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
67.00 %
11
Not Available
Allotropes
Yes
No
α Allotropes
α-Cobalt
Not Available
β Allotropes
β-Cobalt
Not Available
γ Allotropes
Not Available
Not Available
Chemical Properties
Chemical Formula
Co
Cr
Isotopes
Known Isotopes
26
13
21
18
Electronegativity
Pauling Electronegativity
1.88
12
1.66
18
Sanderson Electronegativity
2.56
1
1.66
14
Allred Rochow Electronegativity
1.70
5
1.56
10
Allen Electronegativity
1.84
10
1.65
19
Electropositivity
Pauling Electropositivity
2.12
99+
2.34
36
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+
Electron Work Function
5.00 eV
5
4.50 eV
14
Other Chemical Properties
Chemical Stability, Ionization
Anti Corrosion, Chemical Stability, Ionization, Radioactive Isotopes, Solubility
Atomic Properties
Atomic Number
22
99+
24
99+
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
Number of Protons
22
99+
24
99+
Number of Neutrons
26
99+
28
99+
Number of Electrons
22
99+
24
99+
Radius of an Atom
Atomic Radius
147.00 pm
34
128.00 pm
99+
Covalent Radius
160.00 pm
30
139.00 pm
99+
Van der Waals Radius
200.00 pm
28
200.00 pm
28
Atomic Weight
47.87 amu
99+
52.00 amu
99+
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 Constant
295.08 pm
99+
291.00 pm
99+
Lattice Angles
π/2, π/2, 2 π/3
π/2, π/2, π/2
Lattice C/A Ratio
Not Available
Not Available
Mechanical Properties
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+
6.30 g/cm3
40
Tensile Strength
434.00 MPa
9
689.00 MPa
7
Viscosity
Not Available
Not Available
Vapor Pressure
Vapor Pressure at 1000 K
Not Available
0.00 (Pa)
24
Vapor Pressure at 2000 K
0.98 (Pa)
14
774.00 (Pa)
1
Elasticity properties
Shear Modulus
44.00 GPa
17
115.00 GPa
9
Bulk Modulus
110.00 GPa
15
160.00 GPa
11
Young's Modulus
116.00 GPa
18
279.00 GPa
8
Poisson Ratio
0.32
12
0.21
32
Other Mechanical Properties
Ductile
NA
Magnetic Properties
Magnetic Characteristics
Specific Gravity
4,500.00
1
7.19
99+
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
Thermal Properties
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+
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