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Hafnium vs Rhodium

Hafnium
Rhodium
Rhodium vs Hafnium


Periodic Table
Symbol
Hf   
Rh   
Group Number
4   
14
9   
9
Period Number
6   
5   
Block
d block   
d block   
Element Family
Transition Metal   
Transition Metal   
CAS Number
7440586   
30
7440166   
99+
Space Group Name
P63/mmc   
Fm_ 3m   
Space Group Number
194.00   
5
225.00   
2
Facts
Interesting Facts
  • Hafnium metal is highly reactive, hence not found free in nature.
  • Hafnium metal as predicated after Mendeleev finished his periodic table.
  
  • 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.
  
Sources
By-product Zirconium Refining   
Earth's crust, Found As a By-product, Found in Minerals, Mining   
History
  
  
Who Discovered
Dirk Coster and George de Hevesy   
William Hyde Wollaston   
Discovery
In 1922   
In 1804   
Abundance
  
  
Abundance In Universe
7 * 10-8 %   
25
6 * 10-8 %   
26
Abundance In Sun
~0.0000001 %   
26
~0.0000002 %   
25
Abundance In Meteorites
0.00 %   
37
0.00 %   
36
Abundance In Earth's Crust
0.00 %   
31
0.00 %   
99+
Abundance In Oceans
0.00 %   
27
Not Available   
Uses
Uses & Benefits
  • 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.
  
  • 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.
  
Industrial Uses
Ammunition Industry   
Aerospace Industry, Automobile Industry, Electrical Industry, Electronic Industry   
Medical Uses
NA   
NA   
Other Uses
Alloys, In Nuclear Reactors, Nuclear Research, Research Purposes   
Alloys   
Biological Properties
  
  
Toxicity
Toxic   
NA   
Present in Human Body
No   
No   
Physical Properties
Melting Point
2,150.00 °C   
10
1,966.00 °C   
12
Boiling Point
5,400.00 °C   
5
3,727.00 °C   
17
Appearance
  
  
Physical State
Solid   
Solid   
Color
Gray   
Silvery White   
Luster
Metallic   
Metallic   
Hardness
  
  
Mohs Hardness
5.50   
7
6.00   
6
Brinell Hardness
1,450.00 MPa   
6
980.00 MPa   
9
Vickers Hardness
1,520.00 MPa   
5
1,100.00 MPa   
9
Speed of Sound
3,010.00 m/s   
27
4,700.00 m/s   
15
Optical Properties
  
  
Reflectivity
Not Available   
84.00 %   
4
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
Hf   
Rh   
Isotopes
  
  
Known Isotopes
32   
7
16   
23
Electronegativity
  
  
Pauling Electronegativity
1.30   
32
2.28   
3
Allred Rochow Electronegativity
1.23   
25
1.45   
16
Allen Electronegativity
1.16   
37
1.56   
24
Electropositivity
  
  
Pauling Electropositivity
2.70   
22
1.72   
99+
Ionization Energies
  
  
1st Energy Level
658.50 kJ/mol   
40
719.70 kJ/mol   
29
2nd Energy Level
1,440.00 kJ/mol   
99+
1,740.00 kJ/mol   
26
3rd Energy Level
2,250.00 kJ/mol   
99+
2,997.00 kJ/mol   
27
4th Energy Level
3,216.00 kJ/mol   
99+
Not Available   
Electrochemical Equivalent
1.66 g/amp-hr   
99+
1.28 g/amp-hr   
99+
Electron Work Function
3.90 eV   
27
4.98 eV   
6
Other Chemical Properties
Anti Corrosion, Ionization, Radioactive Isotopes, Solubility   
Anti Corrosion, Ionization, Radioactive Isotopes   
Atomic Properties
Atomic Number
72   
99+
45   
99+
Electron Configuration
[Xe] 4f14 5d2 6s2   
[Kr] 4d8 5s1   
Crystal Structure
Hexagonal Close Packed (HCP)   
Face Centered Cubic (FCC)   
Crystal Lattice
BCC-Crystal-Structure-.jpg#100   
FCC-Crystal-Structure-of-Rhodium.jpg#100   
Atom
  
  
Number of Protons
72   
99+
45   
99+
Number of Neutrons
106   
29
58   
99+
Number of Electrons
72   
99+
45   
99+
Radius of an Atom
  
  
Atomic Radius
159.00 pm   
28
134.00 pm   
99+
Covalent Radius
175.00 pm   
23
142.00 pm   
99+
Van der Waals Radius
200.00 pm   
28
200.00 pm   
28
Atomic Weight
178.49 amu   
39
102.91 amu   
99+
Atomic Volume
13.60 cm3/mol   
38
8.30 cm3/mol   
99+
Adjacent Atomic Numbers
  
  
Previous Element
Lutetium
  
Ruthenium
  
Next Element
Tantalum
  
Palladium
  
Valence Electron Potential
81.00 (-eV)   
16
64.00 (-eV)   
22
Lattice Constant
319.64 pm   
99+
380.34 pm   
27
Lattice Angles
π/2, π/2, 2 π/3   
π/2, π/2, π/2   
Lattice C/A Ratio
1.58   
12
Not Available   
Mechanical Properties
Density
  
  
Density At Room Temperature
13.31 g/cm3   
26
12.41 g/cm3   
28
Density When Liquid (at m.p.)
12.00 g/cm3   
12
10.70 g/cm3   
14
Tensile Strength
445.00 MPa   
8
951.00 MPa   
5
Viscosity
Not Available   
Not Available   
Vapor Pressure
  
  
Vapor Pressure at 2000 K
0.00 (Pa)   
24
0.02 (Pa)   
19
Elasticity properties
  
  
Shear Modulus
30.00 GPa   
23
150.00 GPa   
6
Bulk Modulus
110.00 GPa   
15
275.00 GPa   
5
Young's Modulus
78.00 GPa   
25
380.00 GPa   
5
Poisson Ratio
0.37   
7
0.26   
22
Other Mechanical Properties
Ductile, Malleable   
Malleable   
Magnetic Properties
Magnetic Characteristics
  
  
Specific Gravity
13.31   
18
12.41   
20
Magnetic Ordering
Paramagnetic   
Paramagnetic   
Electrical Properties
  
  
Electrical Property
Conductor   
Conductor   
Resistivity
331.00 nΩ·m   
14
43.30 nΩ·m   
99+
Electrical Conductivity
0.03 106/cm Ω   
39
0.21 106/cm Ω   
8
Electron Affinity
0.00 kJ/mol   
40
109.70 kJ/mol   
7
Thermal Properties
Specific Heat
0.14 J/(kg K)   
37
0.24 J/(kg K)   
22
Molar Heat Capacity
25.73 J/mol·K   
36
24.98 J/mol·K   
99+
Thermal Conductivity
23.00 W/m·K   
99+
150.00 W/m·K   
9
Critical Temperature
Not Available   
Not Available   
Thermal Expansion
5.90 µm/(m·K)   
99+
8.20 µm/(m·K)   
99+
Enthalpy
  
  
Enthalpy of Vaporization
661.10 kJ/mol   
5
495.40 kJ/mol   
12
Enthalpy of Fusion
25.10 kJ/mol   
8
21.76 kJ/mol   
10
Enthalpy of Atomization
703.00 kJ/mol   
5
556.50 kJ/mol   
12
Standard Molar Entropy
43.60 J/mol.K   
34
31.50 J/mol.K   
99+
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