Rhodium Osmium Comparison
Periodic Table
Symbol
Rh
Os
Group Number
9
9
8
10
Period Number
5
6
Block
d block
d block
Element Family
Transition Metal
Transition Metal
CAS Number
7440166
99+
7440042
99+
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.
- Osmium metal does not oxidize in air unless it is heated.
- But if it heated den it forms Osmium Tetroxide, which is highly toxic.
Sources
Earth's crust, Found As a By-product, Found in Minerals, Mining
Found As a By-product, Found in Minerals, Mining
History
Who Discovered
William Hyde Wollaston
Smithson Tennant
Discovery
In 1804
In 1803
Abundance
Abundance In Universe
6 * 10-8 %
26
3 * 10-7 %
21
Abundance In Sun
~0.0000002 %
25
~0.0000002 %
25
Abundance In Meteorites
0.00 %
36
0.00 %
28
Abundance In Earth's Crust
0.00 %
99+
0.00 %
99+
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 has very limited uses and its alloys are very hard and are used in the manufacturing of pen tips, pivots, needles and electrical contacts.
- It is also used as industrial catalyst to speed up the chemical reaction.
Industrial Uses
Aerospace Industry, 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
NA
Highly Toxic
Present in Human Body
No
No
Physical Properties
Melting Point
1,966.00 °C
12
3,045.00 °C
3
Boiling Point
3,727.00 °C
17
5,027.00 °C
6
Appearance
Physical State
Solid
Solid
Color
Silvery White
Silvery Bluish-Gray
Luster
Metallic
Metallic
Hardness
Mohs Hardness
6.00
6
7.00
3
Brinell Hardness
980.00 MPa
9
3,490.00 MPa
1
Vickers Hardness
1,100.00 MPa
9
Not Available
Speed of Sound
4,700.00 m/s
15
4,940.00 m/s
11
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
Os
Isotopes
Known Isotopes
16
23
35
4
Electronegativity
Pauling Electronegativity
2.28
3
2.20
4
Allred Rochow Electronegativity
1.45
16
1.52
12
Allen Electronegativity
1.56
24
1.65
19
Electropositivity
Pauling Electropositivity
1.72
99+
1.80
99+
Ionization Energies
1st Energy Level
719.70 kJ/mol
29
840.00 kJ/mol
12
2nd Energy Level
1,740.00 kJ/mol
26
1,309.80 kJ/mol
99+
3rd Energy Level
2,997.00 kJ/mol
27
1,600.00 kJ/mol
99+
Electrochemical Equivalent
1.28 g/amp-hr
99+
1.77 g/amp-hr
38
Electron Work Function
4.98 eV
6
4.83 eV
8
Other Chemical Properties
Anti Corrosion, Ionization, Radioactive Isotopes
Chemical Stability, Ionization, Solubility
Atomic Properties
Atomic Number
45
99+
76
40
Electron Configuration
[Kr] 4d8 5s1
[Xe] 4f14 5d6 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+
76
39
Number of Neutrons
58
99+
114
25
Number of Electrons
45
99+
76
39
Radius of an Atom
Atomic Radius
134.00 pm
99+
133.80 pm
99+
Covalent Radius
142.00 pm
99+
Not Available
Van der Waals Radius
200.00 pm
28
216.00 pm
24
Atomic Weight
102.91 amu
99+
190.23 amu
35
Atomic Volume
8.30 cm3/mol
99+
8.49 cm3/mol
99+
Adjacent Atomic Numbers
Valence Electron Potential
64.00 (-eV)
22
91.40 (-eV)
12
Lattice Constant
380.34 pm
27
273.44 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
14
Mechanical Properties
Density
Density At Room Temperature
12.41 g/cm3
28
22.59 g/cm3
9
Density When Liquid (at m.p.)
10.70 g/cm3
14
20.00 g/cm3
1
Tensile Strength
951.00 MPa
5
1,000.00 MPa
4
Viscosity
Not Available
Not Available
Vapor Pressure
Vapor Pressure at 2000 K
0.02 (Pa)
19
0.00 (Pa)
28
Elasticity properties
Shear Modulus
150.00 GPa
6
222.00 GPa
1
Bulk Modulus
275.00 GPa
5
462.00 GPa
1
Young's Modulus
380.00 GPa
5
Not Available
Poisson Ratio
0.26
22
0.25
24
Other Mechanical Properties
Malleable
Ductile
Magnetic Properties
Magnetic Characteristics
Specific Gravity
12.41
20
22.57
2
Magnetic Ordering
Paramagnetic
Paramagnetic
Electrical Properties
Electrical Property
Conductor
Conductor
Resistivity
43.30 nΩ·m
99+
81.20 nΩ·m
35
Electrical Conductivity
0.21 106/cm Ω
8
0.11 106/cm Ω
18
Electron Affinity
109.70 kJ/mol
7
106.10 kJ/mol
9
Thermal Properties
Specific Heat
0.24 J/(kg K)
22
0.13 J/(kg K)
39
Molar Heat Capacity
24.98 J/mol·K
99+
24.70 J/mol·K
99+
Thermal Conductivity
150.00 W/m·K
9
87.60 W/m·K
19
Critical Temperature
Not Available
Not Available
Thermal Expansion
8.20 µm/(m·K)
99+
5.10 µm/(m·K)
99+
Enthalpy
Enthalpy of Vaporization
495.40 kJ/mol
12
627.60 kJ/mol
7
Enthalpy of Fusion
21.76 kJ/mol
10
29.30 kJ/mol
4
Enthalpy of Atomization
556.50 kJ/mol
12
669.00 kJ/mol
6
Standard Molar Entropy
31.50 J/mol.K
99+
32.60 J/mol.K
99+
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