Symbol
Hf
  
Rh
  
Period Number
6
  
5
  
Block
d block
  
d block
  
Element Family
Transition Metal
  
Transition Metal
  
Space Group Name
P63/mmc
  
Fm_ 3m
  
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 Sun
~0.0000001 %
  
26
~0.0000002 %
  
25
Abundance In Earth's Crust
Abundance In Oceans
Not Available
  
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
  
Melting Point
2,150.00 °C
  
10
1,966.00 °C
  
12
Boiling Point
3,727.00 °C
  
17
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Gray
  
Silvery White
  
Luster
Metallic
  
Metallic
  
Hardness
  
  
Brinell Hardness
1,450.00 MPa
  
6
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
  
Allotropes
No
  
No
  
α Allotropes
Not Available
  
Not Available
  
β Allotropes
Not Available
  
Not Available
  
γ Allotropes
Not Available
  
Not Available
  
Chemical Formula
Hf
  
Rh
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Allred Rochow Electronegativity
Electropositivity
  
  
Pauling Electropositivity
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+
Other Chemical Properties
Anti Corrosion, Ionization, Radioactive Isotopes, Solubility
  
Anti Corrosion, Ionization, Radioactive Isotopes
  
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
  
  
Radius of an Atom
  
  
Atomic Weight
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 Angles
π/2, π/2, 2 π/3
  
π/2, π/2, π/2
  
Lattice C/A Ratio
Not Available
  
Density
  
  
Density At Room Temperature
13.31 g/cm
3
  
26
12.41 g/cm
3
  
28
Density When Liquid (at m.p.)
12.00 g/cm3
  
12
10.70 g/cm3
  
14
Viscosity
Not Available
  
Not Available
  
Vapor Pressure
  
  
Elasticity properties
  
  
Other Mechanical Properties
Ductile, Malleable
  
Malleable
  
Magnetic Characteristics
  
  
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 10
6/cm Ω
  
39
0.21 10
6/cm Ω
  
8
Electron Affinity
0.00 kJ/mol
  
40
109.70 kJ/mol
  
7
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+