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Rhodium vs Molybdenum


Molybdenum vs Rhodium


Periodic Table

Symbol
Rh   
Mo   

Group Number
9   
9
6   
12

Period Number
5   
5   

Block
d block   
d block   

Element Family
Transition Metal   
Transition Metal   

CAS Number
7440166   
99+
7439987   
99+

Space Group Name
Fm_ 3m   
Im_ 3m   

Space Group Number
225.00   
2
229.00   
1

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.
  
  • Molybdenum is highly reactive metal, hence not found free in nature .
  • Till 18th century Molybdenum element were often mistaken as a carbon or Lead.
  

Sources
Earth's crust, Found As a By-product, Found in Minerals, Mining   
Found in Minerals, Mining, Ores of Minerals   

History
  
  

Who Discovered
William Hyde Wollaston   
Carl Wilhelm Scheele   

Discovery
In 1804   
In 1778   

Abundance
  
  

Abundance In Universe
6 * 10-8 %   
26
5 * 10-7 %   
19

Abundance In Sun
~0.0000002 %   
25
~0.0000009 %   
19

Abundance In Meteorites
0.00 %   
36
0.00 %   
24

Abundance In Earth's Crust
0.00 %   
99+
0.00 %   
39

Abundance In Oceans
Not Available   
0.00 %   
9

Abundance In Humans
Not Available   
0.00 %   
14

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 are used to make engine parts, drills, saw blade, etc.
  • Lubricant additive made up of Molybdenum disulfide is commonly used in the industry. It is also used as a catalyst.
  

Industrial Uses
Aerospace Industry, Automobile Industry, Electrical Industry, Electronic Industry   
Aerospace Industry, Electrical Industry, Electronic Industry   

Medical Uses
NA   
NA   

Other Uses
Alloys   
Alloys   

Biological Properties
  
  

Toxicity
NA   
Toxic   

Present in Human Body
No   
Yes   

In Blood
Not Available   
0.00 Blood/mg dm-3   
31

In Bone
Not Available   
0.70 p.p.m.   
18

Physical Properties

Melting Point
1,966.00 °C   
12
2,617.00 °C   
5

Boiling Point
3,727.00 °C   
17
4,612.00 °C   
9

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
1,370.00 MPa   
7

Vickers Hardness
1,100.00 MPa   
9
1,400.00 MPa   
6

Speed of Sound
4,700.00 m/s   
15
5,400.00 m/s   
6

Optical Properties
  
  

Reflectivity
84.00 %   
4
58.00 %   
15

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   
Mo   

Isotopes
  
  

Known Isotopes
16   
23
25   
14

Electronegativity
  
  

Pauling Electronegativity
2.28   
3
2.16   
5

Sanderson Electronegativity
Not Available   
1.15   
19

Allred Rochow Electronegativity
1.45   
16
1.30   
24

Allen Electronegativity
1.56   
24
2.16   
3

Electropositivity
  
  

Pauling Electropositivity
1.72   
99+
1.84   
99+

Ionization Energies
  
  

1st Energy Level
719.70 kJ/mol   
29
684.30 kJ/mol   
37

2nd Energy Level
1,740.00 kJ/mol   
26
1,560.00 kJ/mol   
37

3rd Energy Level
2,997.00 kJ/mol   
27
2,618.00 kJ/mol   
99+

4th Energy Level
Not Available   
4,480.00 kJ/mol   
26

5th Energy Level
Not Available   
5,257.00 kJ/mol   
32

6th Energy Level
Not Available   
6,640.80 kJ/mol   
22

7th Energy level
Not Available   
12,125.00 kJ/mol   
13

8th Energy Level
Not Available   
13,860.00 kJ/mol   
16

9th Energy Level
Not Available   
15,835.00 kJ/mol   
16

10th Energy Level
Not Available   
17,980.00 kJ/mol   
18

11th Energy Level
Not Available   
20,190.00 kJ/mol   
17

12th Energy Level
Not Available   
22,219.00 kJ/mol   
15

13th Energy Level
Not Available   
26,930.00 kJ/mol   
13

14th Energy Level
Not Available   
29,196.00 kJ/mol   
13

15th Energy Level
Not Available   
52,490.00 kJ/mol   
7

16th Energy Level
Not Available   
55,000.00 kJ/mol   
8

17th Energy Level
Not Available   
61,400.00 kJ/mol   
9

18th Energy Level
Not Available   
67,700.00 kJ/mol   
9

19th Energy Level
Not Available   
74,000.00 kJ/mol   
9

20th Energy Level
Not Available   
80,400.00 kJ/mol   
10

21st Energy Level
Not Available   
87,000.00 kJ/mol   
9

22nd Energy Level
Not Available   
93,400.00 kJ/mol   
7

23rd Energy Level
Not Available   
98,420.00 kJ/mol   
6

24th Energy Level
Not Available   
104,400.00 kJ/mol   
2

25th Energy Level
Not Available   
121,900.00 kJ/mol   
1

26th Energy Level
Not Available   
127,700.00 kJ/mol   
1

27th Energy Level
Not Available   
133,800.00 kJ/mol   
1

28th Energy Level
Not Available   
139,800.00 kJ/mol   
1

29th Energy Level
Not Available   
148,100.00 kJ/mol   
1

30th Energy Level
Not Available   
154,500.00 kJ/mol   
1

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

Electron Work Function
4.98 eV   
6
4.60 eV   
12

Other Chemical Properties
Anti Corrosion, Ionization, Radioactive Isotopes   
Anti Corrosion, Ionization, Radioactive Isotopes, Solubility   

Atomic Properties

Atomic Number
45   
99+
42   
99+

Electron Configuration
[Kr] 4d8 5s1   
[Kr] 4d5 5s1   

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

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

Atom
  
  

Number of Protons
45   
99+
42   
99+

Number of Neutrons
58   
99+
54   
99+

Number of Electrons
45   
99+
42   
99+

Radius of an Atom
  
  

Atomic Radius
134.00 pm   
99+
139.00 pm   
39

Covalent Radius
142.00 pm   
99+
154.00 pm   
32

Van der Waals Radius
200.00 pm   
28
200.00 pm   
28

Atomic Weight
102.91 amu   
99+
95.95 amu   
99+

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

Adjacent Atomic Numbers
  
  

Previous Element
Ruthenium
  
Niobium
  

Next Element
Palladium
  
Technetium
  

Valence Electron Potential
64.00 (-eV)   
22
88.60 (-eV)   
13

Lattice Constant
380.34 pm   
27
314.70 pm   
99+

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
12.41 g/cm3   
28
10.28 g/cm3   
36

Density When Liquid (at m.p.)
10.70 g/cm3   
14
9.33 g/cm3   
20

Tensile Strength
951.00 MPa   
5
324.00 MPa   
13

Viscosity
Not Available   
Not Available   

Vapor Pressure
  
  

Vapor Pressure at 2000 K
0.02 (Pa)   
19
0.00 (Pa)   
26

Elasticity properties
  
  

Shear Modulus
150.00 GPa   
6
126.00 GPa   
8

Bulk Modulus
275.00 GPa   
5
230.00 GPa   
6

Young's Modulus
380.00 GPa   
5
329.00 GPa   
6

Poisson Ratio
0.26   
22
0.31   
13

Other Mechanical Properties
Malleable   
Ductile, Weldable   

Magnetic Properties

Magnetic Characteristics
  
  

Specific Gravity
12.41   
20
10.22   
27

Magnetic Ordering
Paramagnetic   
Paramagnetic   

Electrical Properties
  
  

Electrical Property
Conductor   
Semiconductor   

Resistivity
43.30 nΩ·m   
99+
53.40 nΩ·m   
99+

Electrical Conductivity
0.21 106/cm Ω   
8
0.19 106/cm Ω   
11

Electron Affinity
109.70 kJ/mol   
7
71.90 kJ/mol   
14

Thermal Properties

Specific Heat
0.24 J/(kg K)   
22
0.25 J/(kg K)   
21

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

Thermal Conductivity
150.00 W/m·K   
9
138.00 W/m·K   
12

Critical Temperature
Not Available   
Not Available   

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

Enthalpy
  
  

Enthalpy of Vaporization
495.40 kJ/mol   
12
594.10 kJ/mol   
8

Enthalpy of Fusion
21.76 kJ/mol   
10
27.61 kJ/mol   
5

Enthalpy of Atomization
556.50 kJ/mol   
12
653.00 kJ/mol   
7

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

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