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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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