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Rhodium vs Hafnium

Rhodium
Hafnium
Hafnium vs Rhodium


Periodic Table
Symbol
Rh  
Hf  
Group Number
9  
9
4  
14
Period Number
5  
6  
Block
d block  
d block  
Element Family
Transition Metal  
Transition Metal  
CAS Number
7440166  
99+
7440586  
30
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.
  
  • Hafnium metal is highly reactive, hence not found free in nature.
  • Hafnium metal as predicated after Mendeleev finished his periodic table.
  
Sources
Earth's crust, Found As a By-product, Found in Minerals, Mining  
By-product Zirconium Refining  
History
  
  
Who Discovered
William Hyde Wollaston  
Dirk Coster and George de Hevesy  
Discovery
In 1804  
In 1922  
Abundance
  
  
Abundance In Universe
6 * 10-8 %  
26
7 * 10-8 %  
25
Abundance In Sun
~0.0000002 %  
25
~0.0000001 %  
26
Abundance In Meteorites
0.00 %  
36
0.00 %  
37
Abundance In Earth's Crust
0.00 %  
99+
0.00 %  
31
Abundance In Oceans
Not Available  
0.00 %  
27
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.
  
  • It has an ability to absorb neutrons and hence it is used to make control rods in nuclear submarines. And this metal is also used in Plasma welding torches.
  • It alloys with iron, titanium and niobium are very useful.
  
Industrial Uses
Aerospace Industry, Automobile Industry, Electrical Industry, Electronic Industry  
Ammunition Industry  
Medical Uses
NA  
NA  
Other Uses
Alloys  
Alloys, In Nuclear Reactors, Nuclear Research, Research Purposes  
Biological Properties
  
  
Toxicity
NA  
Toxic  
Present in Human Body
No  
No  
Physical Properties
Melting Point
1,966.00 °C  
12
2,150.00 °C  
10
Boiling Point
3,727.00 °C  
17
5,400.00 °C  
5
Appearance
  
  
Physical State
Solid  
Solid  
Color
Silvery White  
Gray  
Luster
Metallic  
Metallic  
Hardness
  
  
Mohs Hardness
6.00  
6
5.50  
7
Brinell Hardness
980.00 MPa  
9
1,450.00 MPa  
6
Vickers Hardness
1,100.00 MPa  
9
1,520.00 MPa  
5
Speed of Sound
4,700.00 m/s  
15
3,010.00 m/s  
27
Optical Properties
  
  
Reflectivity
84.00 %  
4
Not Available  
Allotropes
No  
No  
α Allotropes
Not Available  
Not Available  
β Allotropes
Not Available  
Not Available  
γ Allotropes
Not Available  
Not Available  
Chemical Properties
Chemical Formula
Rh  
Hf  
Isotopes
  
  
Known Isotopes
16  
23
32  
7
Electronegativity
  
  
Pauling Electronegativity
2.28  
3
1.30  
32
Allred Rochow Electronegativity
1.45  
16
1.23  
25
Allen Electronegativity
1.56  
24
1.16  
37
Electropositivity
  
  
Pauling Electropositivity
1.72  
99+
2.70  
22
Ionization Energies
  
  
1st Energy Level
719.70 kJ/mol  
29
658.50 kJ/mol  
40
2nd Energy Level
1,740.00 kJ/mol  
26
1,440.00 kJ/mol  
99+
3rd Energy Level
2,997.00 kJ/mol  
27
2,250.00 kJ/mol  
99+
4th Energy Level
Not Available  
3,216.00 kJ/mol  
99+
Electrochemical Equivalent
1.28 g/amp-hr  
99+
1.66 g/amp-hr  
99+
Electron Work Function
4.98 eV  
6
3.90 eV  
27
Other Chemical Properties
Anti Corrosion, Ionization, Radioactive Isotopes  
Anti Corrosion, Ionization, Radioactive Isotopes, Solubility  
Atomic Properties
Atomic Number
45  
99+
72  
99+
Electron Configuration
[Kr] 4d8 5s1  
[Xe] 4f14 5d2 6s2  
Crystal Structure
Face Centered Cubic (FCC)  
Hexagonal Close Packed (HCP)  
Crystal Lattice
FCC-Crystal-Structure-of-Rhodium.jpg#100  
BCC-Crystal-Structure-.jpg#100  
Atom
  
  
Number of Protons
45  
99+
72  
99+
Number of Neutrons
58  
99+
106  
29
Number of Electrons
45  
99+
72  
99+
Radius of an Atom
  
  
Atomic Radius
134.00 pm  
99+
159.00 pm  
28
Covalent Radius
142.00 pm  
99+
175.00 pm  
23
Van der Waals Radius
200.00 pm  
28
200.00 pm  
28
Atomic Weight
102.91 amu  
99+
178.49 amu  
39
Atomic Volume
8.30 cm3/mol  
99+
13.60 cm3/mol  
38
Adjacent Atomic Numbers
  
  
Previous Element
Ruthenium
  
Lutetium
  
Next Element
Palladium
  
Tantalum
  
Valence Electron Potential
64.00 (-eV)  
22
81.00 (-eV)  
16
Lattice Constant
380.34 pm  
27
319.64 pm  
99+
Lattice Angles
π/2, π/2, π/2  
π/2, π/2, 2 π/3  
Lattice C/A Ratio
Not Available  
1.58  
12
Mechanical Properties
Density
  
  
Density At Room Temperature
12.41 g/cm3  
28
13.31 g/cm3  
26
Density When Liquid (at m.p.)
10.70 g/cm3  
14
12.00 g/cm3  
12
Tensile Strength
951.00 MPa  
5
445.00 MPa  
8
Viscosity
Not Available  
Not Available  
Vapor Pressure
  
  
Vapor Pressure at 2000 K
0.02 (Pa)  
19
0.00 (Pa)  
24
Elasticity properties
  
  
Shear Modulus
150.00 GPa  
6
30.00 GPa  
23
Bulk Modulus
275.00 GPa  
5
110.00 GPa  
15
Young's Modulus
380.00 GPa  
5
78.00 GPa  
25
Poisson Ratio
0.26  
22
0.37  
7
Other Mechanical Properties
Malleable  
Ductile, Malleable  
Magnetic Properties
Magnetic Characteristics
  
  
Specific Gravity
12.41  
20
13.31  
18
Magnetic Ordering
Paramagnetic  
Paramagnetic  
Electrical Properties
  
  
Electrical Property
Conductor  
Conductor  
Resistivity
43.30 nΩ·m  
99+
331.00 nΩ·m  
14
Electrical Conductivity
0.21 106/cm Ω  
8
0.03 106/cm Ω  
39
Electron Affinity
109.70 kJ/mol  
7
0.00 kJ/mol  
40
Thermal Properties
Specific Heat
0.24 J/(kg K)  
22
0.14 J/(kg K)  
37
Molar Heat Capacity
24.98 J/mol·K  
99+
25.73 J/mol·K  
36
Thermal Conductivity
150.00 W/m·K  
9
23.00 W/m·K  
99+
Critical Temperature
Not Available  
Not Available  
Thermal Expansion
8.20 µm/(m·K)  
99+
5.90 µm/(m·K)  
99+
Enthalpy
  
  
Enthalpy of Vaporization
495.40 kJ/mol  
12
661.10 kJ/mol  
5
Enthalpy of Fusion
21.76 kJ/mol  
10
25.10 kJ/mol  
8
Enthalpy of Atomization
556.50 kJ/mol  
12
703.00 kJ/mol  
5
Standard Molar Entropy
31.50 J/mol.K  
99+
43.60 J/mol.K  
34
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