Hafnium vs Rhodium
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
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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