Chromium vs Cobalt
Periodic Table
Symbol
Cr
Co
Group Number
6
12
9
9
Period Number
4
4
Block
d block
d block
Element Family
Transition Metal
Transition Metal
CAS Number
7440473
39
7440484
38
Space Group Name
Im_ 3m
P63/mmc
Space Group Number
229.00
1
194.00
5
Facts
Interesting Facts
- 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.
- 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.
Sources
Found in Minerals, Mining, Ores of metals, Ores of Minerals
Found in Compounds, Mining, Ores of Minerals
History
Who Discovered
Louis Nicolas Vauquelin
Georg Brandt
Discovery
In Between 1797 - 1798
In 1732
Abundance
Abundance In Universe
1.5 * 10-3 %
7
3 * 10-4 %
9
Abundance In Sun
~0.002 %
7
~0.0004 %
9
Abundance In Meteorites
0.30 %
7
0.06 %
10
Abundance In Earth's Crust
0.01 %
13
0.00 %
21
Abundance In Oceans
0.00 %
16
0.00 %
20
Abundance In Humans
0.00 %
16
0.00 %
17
Uses
Uses & Benefits
- 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.
- 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.
Industrial Uses
Automobile Industry, Chemical Industry
Chemical Industry, Electrical Industry, Electronic Industry
Medical Uses
NA
Pharmaceutical Industry
Other Uses
Alloys
Alloys
Biological Properties
Toxicity
Highly Toxic
Toxic
Present in Human Body
Yes
Yes
In Blood
0.11 Blood/mg dm-3
12
0.04 Blood/mg dm-3
18
In Bone
0.33 p.p.m.
21
0.04 p.p.m.
27
Physical Properties
Melting Point
1,857.00 °C
14
1,495.00 °C
29
Boiling Point
2,672.00 °C
39
2,870.00 °C
34
Appearance
Physical State
Solid
Solid
Color
Silver
Gray
Luster
Metallic
Metallic
Hardness
Mohs Hardness
8.50
1
5.00
8
Brinell Hardness
687.00 MPa
16
470.00 MPa
26
Vickers Hardness
1,060.00 MPa
10
1,043.00 MPa
11
Speed of Sound
5,940.00 m/s
5
4,720.00 m/s
14
Optical Properties
Reflectivity
Not Available
67.00 %
11
Allotropes
No
Yes
α Allotropes
Not Available
α-Cobalt
β Allotropes
Not Available
β-Cobalt
γ Allotropes
Not Available
Not Available
Chemical Properties
Chemical Formula
Cr
Co
Isotopes
Known Isotopes
21
18
26
13
Electronegativity
Pauling Electronegativity
1.66
18
1.88
12
Sanderson Electronegativity
1.66
14
2.56
1
Allred Rochow Electronegativity
1.56
10
1.70
5
Allen Electronegativity
1.65
19
1.84
10
Electropositivity
Pauling Electropositivity
2.34
36
2.12
99+
Ionization Energies
1st Energy Level
26,130.00 kJ/mol
1
760.40 kJ/mol
19
2nd Energy Level
28,750.00 kJ/mol
1
1,648.00 kJ/mol
31
3rd Energy Level
34,230.00 kJ/mol
1
3,232.00 kJ/mol
22
4th Energy Level
37,066.00 kJ/mol
1
4,950.00 kJ/mol
19
5th Energy Level
97,510.00 kJ/mol
1
7,670.00 kJ/mol
12
6th Energy Level
105,800.00 kJ/mol
1
9,840.00 kJ/mol
12
7th Energy level
114,300.00 kJ/mol
1
12,440.00 kJ/mol
11
8th Energy Level
125,300.00 kJ/mol
1
15,230.00 kJ/mol
12
9th Energy Level
134,700.00 kJ/mol
1
17,959.00 kJ/mol
13
10th Energy Level
144,300.00 kJ/mol
1
26,570.00 kJ/mol
7
11th Energy Level
26,130.00 kJ/mol
12
29,400.00 kJ/mol
8
12th Energy Level
28,750.00 kJ/mol
13
32,400.00 kJ/mol
8
13th Energy Level
34,230.00 kJ/mol
10
36,600.00 kJ/mol
8
14th Energy Level
37,066.00 kJ/mol
12
39,700.00 kJ/mol
9
15th Energy Level
97,510.00 kJ/mol
1
42,800.00 kJ/mol
12
16th Energy Level
105,800.00 kJ/mol
2
49,396.00 kJ/mol
11
17th Energy Level
114,300.00 kJ/mol
3
52,737.00 kJ/mol
13
18th Energy Level
125,300.00 kJ/mol
4
134,810.00 kJ/mol
1
19th Energy Level
134,700.00 kJ/mol
5
145,170.00 kJ/mol
2
20th Energy Level
144,300.00 kJ/mol
7
154,700.00 kJ/mol
4
21st Energy Level
157,700.00 kJ/mol
7
167,400.00 kJ/mol
4
22nd Energy Level
166,090.00 kJ/mol
6
178,100.00 kJ/mol
3
23rd Energy Level
Not Available
189,300.00 kJ/mol
3
Electrochemical Equivalent
0.32 g/amp-hr
99+
1.10 g/amp-hr
99+
Electron Work Function
4.50 eV
14
5.00 eV
5
Other Chemical Properties
Anti Corrosion, Chemical Stability, Ionization, Radioactive Isotopes, Solubility
Chemical Stability, Ionization
Atomic Properties
Atomic Number
24
99+
22
99+
Electron Configuration
[Ar] 3d5 4s1
[Ar] 3d2 4s2
Crystal Structure
Body Centered Cubic (BCC)
Hexagonal Close Packed (HCP)
Crystal Lattice
BCC-Crystal-Structure-.jpg#100
HCP-Crystal-Structure-of-Cobalt.jpg#100
Atom
Number of Protons
24
99+
22
99+
Number of Neutrons
28
99+
26
99+
Number of Electrons
24
99+
22
99+
Radius of an Atom
Atomic Radius
128.00 pm
99+
147.00 pm
34
Covalent Radius
139.00 pm
99+
160.00 pm
30
Van der Waals Radius
200.00 pm
28
200.00 pm
28
Atomic Weight
52.00 amu
99+
47.87 amu
99+
Atomic Volume
7.23 cm3/mol
99+
10.64 cm3/mol
99+
Adjacent Atomic Numbers
Valence Electron Potential
170.00 (-eV)
4
95.20 (-eV)
10
Lattice Constant
291.00 pm
99+
295.08 pm
99+
Lattice Angles
π/2, π/2, π/2
π/2, π/2, 2 π/3
Lattice C/A Ratio
Not Available
Not Available
Mechanical Properties
Density
Density At Room Temperature
7.19 g/cm3
99+
4.51 g/cm3
99+
Density When Liquid (at m.p.)
6.30 g/cm3
40
4.11 g/cm3
99+
Tensile Strength
689.00 MPa
7
434.00 MPa
9
Viscosity
Not Available
Not Available
Vapor Pressure
Vapor Pressure at 1000 K
0.00 (Pa)
24
Not Available
Vapor Pressure at 2000 K
774.00 (Pa)
1
0.98 (Pa)
14
Elasticity properties
Shear Modulus
115.00 GPa
9
44.00 GPa
17
Bulk Modulus
160.00 GPa
11
110.00 GPa
15
Young's Modulus
279.00 GPa
8
116.00 GPa
18
Poisson Ratio
0.21
32
0.32
12
Other Mechanical Properties
NA
Ductile
Magnetic Properties
Magnetic Characteristics
Specific Gravity
7.19
99+
4,500.00
1
Magnetic Ordering
Antiferromagnetic
Paramagnetic
Electrical Properties
Electrical Property
NA
Poor Conductor
Resistivity
125.00 nΩ·m
27
420.00 nΩ·m
12
Electrical Conductivity
0.08 106/cm Ω
25
0.02 106/cm Ω
99+
Electron Affinity
64.30 kJ/mol
15
7.60 kJ/mol
37
Thermal Properties
Specific Heat
0.45 J/(kg K)
12
0.52 J/(kg K)
9
Molar Heat Capacity
23.35 J/mol·K
99+
25.06 J/mol·K
99+
Thermal Conductivity
93.90 W/m·K
17
21.90 W/m·K
99+
Critical Temperature
Not Available
Not Available
Thermal Expansion
4.90 µm/(m·K)
99+
8.60 µm/(m·K)
99+
Enthalpy
Enthalpy of Vaporization
348.80 kJ/mol
24
429.00 kJ/mol
15
Enthalpy of Fusion
15.31 kJ/mol
20
15.48 kJ/mol
19
Enthalpy of Atomization
397.50 kJ/mol
21
468.60 kJ/mol
15
Standard Molar Entropy
23.80 J/mol.K
99+
27.30 J/mol.K
99+
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