Rhodium vs Cobalt
Periodic Table
Symbol
Rh
Co
Group Number
9
9
9
9
Period Number
5
4
Block
d block
d block
Element Family
Transition Metal
Transition Metal
CAS Number
7440166
99+
7440484
38
Space Group Name
Fm_ 3m
P63/mmc
Space Group Number
225.00
2
194.00
5
Facts
Interesting Facts
- Rhodium is the rarest element out of all non-radioactive metals on the earth .
- Rhodium is one of the most durable and hard metal, which also have high reflectance.
- 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
Earth's crust, Found As a By-product, Found in Minerals, Mining
Found in Compounds, Mining, Ores of Minerals
History
Who Discovered
William Hyde Wollaston
Georg Brandt
Discovery
In 1804
In 1732
Abundance
Abundance In Universe
6 * 10-8 %
26
3 * 10-4 %
9
Abundance In Sun
~0.0000002 %
25
~0.0004 %
9
Abundance In Meteorites
0.00 %
36
0.06 %
10
Abundance In Earth's Crust
0.00 %
99+
0.00 %
21
Abundance In Oceans
Not Available
0.00 %
20
Abundance In Humans
Not Available
0.00 %
17
Uses
Uses & Benefits
- Rhodium metal is mainly used in catalytic converters for cars as it reduces nitrogen oxides in exhaust gases.
- It is used as an industrial catalyst for nitric acid, acetic acid, hydrogenation reaction, etc.
- 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
Aerospace Industry, Automobile Industry, Electrical Industry, Electronic Industry
Chemical Industry, Electrical Industry, Electronic Industry
Medical Uses
NA
Pharmaceutical Industry
Other Uses
Alloys
Alloys
Biological Properties
Toxicity
NA
Toxic
Present in Human Body
No
Yes
In Blood
Not Available
0.04 Blood/mg dm-3
18
In Bone
Not Available
0.04 p.p.m.
27
Physical Properties
Melting Point
1,966.00 °C
12
1,495.00 °C
29
Boiling Point
3,727.00 °C
17
2,870.00 °C
34
Appearance
Physical State
Solid
Solid
Color
Silvery White
Gray
Luster
Metallic
Metallic
Hardness
Mohs Hardness
6.00
6
5.00
8
Brinell Hardness
980.00 MPa
9
470.00 MPa
26
Vickers Hardness
1,100.00 MPa
9
1,043.00 MPa
11
Speed of Sound
4,700.00 m/s
15
4,720.00 m/s
14
Optical Properties
Reflectivity
84.00 %
4
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
Rh
Co
Isotopes
Known Isotopes
16
23
26
13
Electronegativity
Pauling Electronegativity
2.28
3
1.88
12
Sanderson Electronegativity
Not Available
2.56
1
Allred Rochow Electronegativity
1.45
16
1.70
5
Allen Electronegativity
1.56
24
1.84
10
Electropositivity
Pauling Electropositivity
1.72
99+
2.12
99+
Ionization Energies
1st Energy Level
719.70 kJ/mol
29
760.40 kJ/mol
19
2nd Energy Level
1,740.00 kJ/mol
26
1,648.00 kJ/mol
31
3rd Energy Level
2,997.00 kJ/mol
27
3,232.00 kJ/mol
22
4th Energy Level
Not Available
4,950.00 kJ/mol
19
5th Energy Level
Not Available
7,670.00 kJ/mol
12
6th Energy Level
Not Available
9,840.00 kJ/mol
12
7th Energy level
Not Available
12,440.00 kJ/mol
11
8th Energy Level
Not Available
15,230.00 kJ/mol
12
9th Energy Level
Not Available
17,959.00 kJ/mol
13
10th Energy Level
Not Available
26,570.00 kJ/mol
7
11th Energy Level
Not Available
29,400.00 kJ/mol
8
12th Energy Level
Not Available
32,400.00 kJ/mol
8
13th Energy Level
Not Available
36,600.00 kJ/mol
8
14th Energy Level
Not Available
39,700.00 kJ/mol
9
15th Energy Level
Not Available
42,800.00 kJ/mol
12
16th Energy Level
Not Available
49,396.00 kJ/mol
11
17th Energy Level
Not Available
52,737.00 kJ/mol
13
18th Energy Level
Not Available
134,810.00 kJ/mol
1
19th Energy Level
Not Available
145,170.00 kJ/mol
2
20th Energy Level
Not Available
154,700.00 kJ/mol
4
21st Energy Level
Not Available
167,400.00 kJ/mol
4
22nd Energy Level
Not Available
178,100.00 kJ/mol
3
23rd Energy Level
Not Available
189,300.00 kJ/mol
3
Electrochemical Equivalent
1.28 g/amp-hr
99+
1.10 g/amp-hr
99+
Electron Work Function
4.98 eV
6
5.00 eV
5
Other Chemical Properties
Anti Corrosion, Ionization, Radioactive Isotopes
Chemical Stability, Ionization
Atomic Properties
Atomic Number
45
99+
22
99+
Electron Configuration
[Kr] 4d8 5s1
[Ar] 3d2 4s2
Crystal Structure
Face Centered Cubic (FCC)
Hexagonal Close Packed (HCP)
Crystal Lattice
FCC-Crystal-Structure-of-Rhodium.jpg#100
HCP-Crystal-Structure-of-Cobalt.jpg#100
Atom
Number of Protons
45
99+
22
99+
Number of Neutrons
58
99+
26
99+
Number of Electrons
45
99+
22
99+
Radius of an Atom
Atomic Radius
134.00 pm
99+
147.00 pm
34
Covalent Radius
142.00 pm
99+
160.00 pm
30
Van der Waals Radius
200.00 pm
28
200.00 pm
28
Atomic Weight
102.91 amu
99+
47.87 amu
99+
Atomic Volume
8.30 cm3/mol
99+
10.64 cm3/mol
99+
Adjacent Atomic Numbers
Valence Electron Potential
64.00 (-eV)
22
95.20 (-eV)
10
Lattice Constant
380.34 pm
27
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
12.41 g/cm3
28
4.51 g/cm3
99+
Density When Liquid (at m.p.)
10.70 g/cm3
14
4.11 g/cm3
99+
Tensile Strength
951.00 MPa
5
434.00 MPa
9
Viscosity
Not Available
Not Available
Vapor Pressure
Vapor Pressure at 2000 K
0.02 (Pa)
19
0.98 (Pa)
14
Elasticity properties
Shear Modulus
150.00 GPa
6
44.00 GPa
17
Bulk Modulus
275.00 GPa
5
110.00 GPa
15
Young's Modulus
380.00 GPa
5
116.00 GPa
18
Poisson Ratio
0.26
22
0.32
12
Other Mechanical Properties
Malleable
Ductile
Magnetic Properties
Magnetic Characteristics
Specific Gravity
12.41
20
4,500.00
1
Magnetic Ordering
Paramagnetic
Paramagnetic
Electrical Properties
Electrical Property
Conductor
Poor Conductor
Resistivity
43.30 nΩ·m
99+
420.00 nΩ·m
12
Electrical Conductivity
0.21 106/cm Ω
8
0.02 106/cm Ω
99+
Electron Affinity
109.70 kJ/mol
7
7.60 kJ/mol
37
Thermal Properties
Specific Heat
0.24 J/(kg K)
22
0.52 J/(kg K)
9
Molar Heat Capacity
24.98 J/mol·K
99+
25.06 J/mol·K
99+
Thermal Conductivity
150.00 W/m·K
9
21.90 W/m·K
99+
Critical Temperature
Not Available
Not Available
Thermal Expansion
8.20 µm/(m·K)
99+
8.60 µm/(m·K)
99+
Enthalpy
Enthalpy of Vaporization
495.40 kJ/mol
12
429.00 kJ/mol
15
Enthalpy of Fusion
21.76 kJ/mol
10
15.48 kJ/mol
19
Enthalpy of Atomization
556.50 kJ/mol
12
468.60 kJ/mol
15
Standard Molar Entropy
31.50 J/mol.K
99+
27.30 J/mol.K
99+
|
||
|
||
|
