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Iridium vs Rhodium


Rhodium vs Iridium


Periodic Table

Symbol
Ir   
Rh   

Group Number
9   
9
9   
9

Period Number
6   
5   

Block
d block   
d block   

Element Family
Transition Metal   
Transition Metal   

CAS Number
7439885   
99+
7440166   
99+

Space Group Name
Fm_ 3m   
Fm_ 3m   

Space Group Number
225.00   
2
225.00   
2

Facts

Interesting Facts
  • Iridium element occurs as natural alloys of Platinum and Osmium.
  • Iridium element is known as the most corrosion resistance metal .
  
  • 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
Found in Minerals, Mining, Ores of Minerals   
Earth's crust, Found As a By-product, Found in Minerals, Mining   

History
  
  

Who Discovered
Smithson Tennant   
William Hyde Wollaston   

Discovery
In 1803   
In 1804   

Abundance
  
  

Abundance In Universe
2 * 10-7 %   
22
6 * 10-8 %   
26

Abundance In Sun
~0.0000002 %   
25
~0.0000002 %   
25

Abundance In Meteorites
0.00 %   
29
0.00 %   
36

Abundance In Earth's Crust
0.00 %   
99+
0.00 %   
99+

Uses

Uses & Benefits
  • Iridium has an anti corrosion properties and it is used in special alloy with Osmium metal and that alloy is used in pen tips and compass bearings.
  
  • 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
Automobile Industry, Electrical Industry, Electronic Industry   
Aerospace Industry, Automobile Industry, Electrical Industry, Electronic Industry   

Medical Uses
NA   
NA   

Other Uses
Alloys   
Alloys   

Biological Properties
  
  

Toxicity
Toxic   
NA   

Present in Human Body
Yes   
No   

Physical Properties

Melting Point
2,410.00 °C   
7
1,966.00 °C   
12

Boiling Point
4,527.00 °C   
10
3,727.00 °C   
17

Appearance
  
  

Physical State
Solid   
Solid   

Color
Silvery White   
Silvery White   

Luster
Metallic   
Metallic   

Hardness
  
  

Mohs Hardness
6.50   
5
6.00   
6

Brinell Hardness
1,670.00 MPa   
5
980.00 MPa   
9

Vickers Hardness
1,760.00 MPa   
3
1,100.00 MPa   
9

Speed of Sound
4,825.00 m/s   
13
4,700.00 m/s   
15

Optical Properties
  
  

Reflectivity
78.00 %   
6
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
Ir   
Rh   

Isotopes
  
  

Known Isotopes
34   
5
16   
23

Electronegativity
  
  

Pauling Electronegativity
2.20   
4
2.28   
3

Allred Rochow Electronegativity
1.55   
11
1.45   
16

Allen Electronegativity
1.68   
17
1.56   
24

Electropositivity
  
  

Pauling Electropositivity
1.80   
99+
1.72   
99+

Ionization Energies
  
  

1st Energy Level
880.00 kJ/mol   
9
719.70 kJ/mol   
29

2nd Energy Level
1,600.00 kJ/mol   
35
1,740.00 kJ/mol   
26

3rd Energy Level
Not Available   
2,997.00 kJ/mol   
27

Electrochemical Equivalent
1.14 g/amp-hr   
99+
1.28 g/amp-hr   
99+

Electron Work Function
4.55 eV   
13
4.98 eV   
6

Other Chemical Properties
Flammable, Ionization, Radioactive Isotopes, Radioactivity   
Anti Corrosion, Ionization, Radioactive Isotopes   

Atomic Properties

Atomic Number
77   
39
45   
99+

Electron Configuration
[Xe] 4f14 5d7 6s2   
[Kr] 4d8 5s1   

Crystal Structure
Face Centered Cubic (FCC)   
Face Centered Cubic (FCC)   

Crystal Lattice
FCC-Crystal-Structure-of-Iridium.jpg#100   
FCC-Crystal-Structure-of-Rhodium.jpg#100   

Atom
  
  

Number of Protons
74   
99+
45   
99+

Number of Neutrons
110   
27
58   
99+

Number of Electrons
74   
99+
45   
99+

Radius of an Atom
  
  

Atomic Radius
136.00 pm   
99+
134.00 pm   
99+

Covalent Radius
141.00 pm   
99+
142.00 pm   
99+

Van der Waals Radius
202.00 pm   
27
200.00 pm   
28

Atomic Weight
192.22 amu   
34
102.91 amu   
99+

Atomic Volume
9.53 cm3/mol   
99+
8.30 cm3/mol   
99+

Adjacent Atomic Numbers
  
  

Previous Element
Osmium
  
Ruthenium
  

Next Element
Platinum
  
Palladium
  

Valence Electron Potential
140.00 (-eV)   
5
64.00 (-eV)   
22

Lattice Constant
383.90 pm   
26
380.34 pm   
27

Lattice Angles
π/2, π/2, π/2   
π/2, π/2, π/2   

Lattice C/A Ratio
Not Available   
Not Available   

Mechanical Properties

Density
  
  

Density At Room Temperature
22.56 g/cm3   
10
12.41 g/cm3   
28

Density When Liquid (at m.p.)
19.00 g/cm3   
3
10.70 g/cm3   
14

Tensile Strength
2,000.00 MPa   
2
951.00 MPa   
5

Viscosity
Not Available   
Not Available   

Vapor Pressure
  
  

Vapor Pressure at 2000 K
0.00 (Pa)   
25
0.02 (Pa)   
19

Elasticity properties
  
  

Shear Modulus
210.00 GPa   
2
150.00 GPa   
6

Bulk Modulus
320.00 GPa   
3
275.00 GPa   
5

Young's Modulus
528.00 GPa   
1
380.00 GPa   
5

Poisson Ratio
0.26   
22
0.26   
22

Other Mechanical Properties
NA   
Malleable   

Magnetic Properties

Magnetic Characteristics
  
  

Specific Gravity
21.78   
3
12.41   
20

Magnetic Ordering
Paramagnetic   
Paramagnetic   

Electrical Properties
  
  

Electrical Property
Conductor   
Conductor   

Resistivity
47.10 nΩ·m   
99+
43.30 nΩ·m   
99+

Electrical Conductivity
0.19 106/cm Ω   
10
0.21 106/cm Ω   
8

Electron Affinity
151.00 kJ/mol   
4
109.70 kJ/mol   
7

Thermal Properties

Specific Heat
0.13 J/(kg K)   
39
0.24 J/(kg K)   
22

Molar Heat Capacity
25.10 J/mol·K   
99+
24.98 J/mol·K   
99+

Thermal Conductivity
147.00 W/m·K   
10
150.00 W/m·K   
9

Critical Temperature
Not Available   
Not Available   

Thermal Expansion
6.40 µm/(m·K)   
99+
8.20 µm/(m·K)   
99+

Enthalpy
  
  

Enthalpy of Vaporization
799.10 kJ/mol   
1
495.40 kJ/mol   
12

Enthalpy of Fusion
35.23 kJ/mol   
1
21.76 kJ/mol   
10

Enthalpy of Atomization
837.00 kJ/mol   
1
556.50 kJ/mol   
12

Standard Molar Entropy
35.50 J/mol.K   
99+
31.50 J/mol.K   
99+

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