Symbol
Rh
  
Cd
  
Period Number
5
  
5
  
Block
d block
  
d block
  
Element Family
Transition Metal
  
Transition Metal
  
Space Group Name
Fm_ 3m
  
P63/mmc
  
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.
  
- Naturally occurring minor elements include Cadmium.
- Cadmium is released into atmosphere to control volcanic eruption and forest fires.
- It is used for electroplating of Steel for corrosion resistance.
- It can absorb neutrons and used in nuclear reactor to control atomic fission.
  
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
  
Karl Samuel Leberecht Hermann and Friedrich Stromeyer
  
Discovery
In 1804
  
In 1817
  
Abundance
  
  
Abundance In Sun
~0.0000002 %
  
25
~0.0000006 %
  
21
Abundance In Earth's Crust
Abundance In Oceans
Not Available
  
Abundance In Humans
Not Available
  
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.
  
- It has very limited uses as it is a toxic metal and it can cause birth defects, cancer, etc.
-
Almost 80% of Cadmium metal is used in Nickel cadmium Batteries and now it is getting replaced with nickel hydride.
  
Industrial Uses
Aerospace Industry, Automobile Industry, Electrical Industry, Electronic Industry
  
Aerospace Industry, Ammunition Industry, Chemical 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
  
0.01 Blood/mg dm-3
  
24
In Bone
Not Available
  
1.80 p.p.m.
  
15
Melting Point
1,966.00 °C
  
12
Boiling Point
3,727.00 °C
  
17
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Silvery White
  
Silvery Bluish-Gray
  
Luster
Metallic
  
Metallic
  
Hardness
  
  
Vickers Hardness
1,100.00 MPa
  
9
Not Available
  
Speed of Sound
4,700.00 m/s
  
15
2,310.00 m/s
  
39
Optical Properties
  
  
Allotropes
No
  
No
  
α Allotropes
Not Available
  
Not Available
  
β Allotropes
Not Available
  
Not Available
  
γ Allotropes
Not Available
  
Not Available
  
Chemical Formula
Rh
  
Cd
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Sanderson Electronegativity
Not Available
  
Allred Rochow Electronegativity
Mulliken-Jaffe Electronegativity
Not Available
  
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
719.70 kJ/mol
  
29
867.80 kJ/mol
  
11
2nd Energy Level
1,740.00 kJ/mol
  
26
1,631.40 kJ/mol
  
32
3rd Energy Level
2,997.00 kJ/mol
  
27
3,616.00 kJ/mol
  
13
Electrochemical Equivalent
1.28 g/amp-hr
  
99+
2.10 g/amp-hr
  
27
Other Chemical Properties
Anti Corrosion, Ionization, Radioactive Isotopes
  
Chemical Stability, Anti Corrosion, Ionization, Radioactive Isotopes, Solubility
  
Electron Configuration
[Kr] 4d8 5s1
  
[Kr] 4d10 5s2
  
Crystal Structure
Face Centered Cubic (FCC)
  
Hexagonal Close Packed (HCP)
  
Crystal Lattice
FCC-Crystal-Structure-of-Rhodium.jpg#100
  
HCP-Crystal-Structure-of-Cadmium.jpg#100
  
Atom
  
  
Radius of an Atom
  
  
Atomic Weight
102.91 amu
  
99+
112.41 amu
  
99+
Atomic Volume
8.30 cm3/mol
  
99+
13.10 cm3/mol
  
39
Adjacent Atomic Numbers
  
  
Valence Electron Potential
64.00 (-eV)
  
22
30.00 (-eV)
  
99+
Lattice Angles
π/2, π/2, π/2
  
π/2, π/2, 2 π/3
  
Lattice C/A Ratio
Not Available
  
Density
  
  
Density At Room Temperature
12.41 g/cm3
  
28
8.65 g/cm3
  
99+
Density When Liquid (at m.p.)
10.70 g/cm3
  
14
Viscosity
Not Available
  
Not Available
  
Vapor Pressure
  
  
Vapor Pressure at 2000 K
Not Available
  
Elasticity properties
  
  
Other Mechanical Properties
Malleable
  
Ductile, Malleable
  
Magnetic Characteristics
  
  
Magnetic Ordering
Paramagnetic
  
Diamagnetic
  
Electrical Properties
  
  
Electrical Property
Conductor
  
Semiconductor
  
Resistivity
43.30 nΩ·m
  
99+
Electrical Conductivity
0.21 106/cm Ω
  
8
0.14 106/cm Ω
  
15
Electron Affinity
109.70 kJ/mol
  
7
0.00 kJ/mol
  
40
Specific Heat
0.24 J/(kg K)
  
22
0.23 J/(kg K)
  
26
Molar Heat Capacity
24.98 J/mol·K
  
99+
26.02 J/mol·K
  
32
Thermal Conductivity
150.00 W/m·K
  
9
96.60 W/m·K
  
16
Critical Temperature
Not Available
  
Not Available
  
Thermal Expansion
8.20 µm/(m·K)
  
99+
30.80 µm/(m·K)
  
10
Enthalpy
  
  
Enthalpy of Vaporization
495.40 kJ/mol
  
12
100.00 kJ/mol
  
99+
Enthalpy of Fusion
21.76 kJ/mol
  
10
6.19 kJ/mol
  
99+
Enthalpy of Atomization
556.50 kJ/mol
  
12
113.00 kJ/mol
  
99+
Standard Molar Entropy
31.50 J/mol.K
  
99+
51.80 J/mol.K
  
27