Rhodium Holmium Comparison
Periodic Table
Symbol
Rh
Ho
Group Number
9
9
Not Available
Period Number
5
6
Block
d block
f block
Element Family
Transition Metal
Lanthanide
CAS Number
7440166
99+
7440600
29
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.
- Holmium metal is very soft and malleable.
- Holmium metal is well known for its corrosion resistivity.
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
Marc Delafontaine
Discovery
In 1804
In 1878
Abundance
Abundance In Universe
6 * 10-8 %
26
5 * 10-8 %
27
Abundance In Sun
~0.0000002 %
25
~-9999 %
Abundance In Meteorites
0.00 %
36
0.00 %
99+
Abundance In Earth's Crust
0.00 %
99+
0.00 %
38
Abundance In Oceans
Not Available
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.
- Holmium metal has an ability to absorb neutrons, so this metal is used in nuclear reactors to keep the chain reactions of elements under control.
- Alloys of Holmium are used to produce Magnet.
Industrial Uses
Aerospace Industry, Automobile Industry, Electrical Industry, Electronic Industry
NA
Medical Uses
NA
NA
Other Uses
Alloys
Alloys, Nuclear Research
Biological Properties
Toxicity
NA
Low Toxic
Present in Human Body
No
No
Physical Properties
Melting Point
1,966.00 °C
12
1,461.00 °C
30
Boiling Point
3,727.00 °C
17
2,600.00 °C
99+
Appearance
Physical State
Solid
Solid
Color
Silvery White
Silvery White
Luster
Metallic
Metallic
Hardness
Mohs Hardness
6.00
6
Not Available
Brinell Hardness
980.00 MPa
9
746.00 MPa
13
Vickers Hardness
1,100.00 MPa
9
481.00 MPa
23
Speed of Sound
4,700.00 m/s
15
2,760.00 m/s
30
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
Ho
Isotopes
Known Isotopes
16
23
34
5
Electronegativity
Pauling Electronegativity
2.28
3
1.23
37
Allred Rochow Electronegativity
1.45
16
1.10
30
Allen Electronegativity
1.56
24
Not Available
Electropositivity
Pauling Electropositivity
1.72
99+
2.77
17
Ionization Energies
1st Energy Level
719.70 kJ/mol
29
581.00 kJ/mol
99+
2nd Energy Level
1,740.00 kJ/mol
26
1,140.00 kJ/mol
99+
3rd Energy Level
2,997.00 kJ/mol
27
2,204.00 kJ/mol
99+
4th Energy Level
Not Available
4,100.00 kJ/mol
34
Electrochemical Equivalent
1.28 g/amp-hr
99+
2.02 g/amp-hr
29
Electron Work Function
4.98 eV
6
Not Available
Other Chemical Properties
Anti Corrosion, Ionization, Radioactive Isotopes
Chemical Stability, Anti Corrosion, Ionization, Radioactive Isotopes, Solubility
Atomic Properties
Atomic Number
45
99+
67
99+
Electron Configuration
[Kr] 4d8 5s1
[Xe] 4f11 6s2
Crystal Structure
Face Centered Cubic (FCC)
Hexagonal Close Packed (HCP)
Crystal Lattice
FCC-Crystal-Structure-of-Rhodium.jpg#100
HCP-Crystal-Structure-of-Holmium.jpg#100
Atom
Number of Protons
45
99+
67
99+
Number of Neutrons
58
99+
98
34
Number of Electrons
45
99+
67
99+
Radius of an Atom
Atomic Radius
134.00 pm
99+
176.00 pm
18
Covalent Radius
142.00 pm
99+
192.00 pm
17
Van der Waals Radius
200.00 pm
28
216.00 pm
24
Atomic Weight
102.91 amu
99+
164.93 amu
99+
Atomic Volume
8.30 cm3/mol
99+
18.70 cm3/mol
24
Adjacent Atomic Numbers
Valence Electron Potential
64.00 (-eV)
22
47.90 (-eV)
31
Lattice Constant
380.34 pm
27
357.73 pm
38
Lattice Angles
π/2, π/2, π/2
π/2, π/2, 2 π/3
Lattice C/A Ratio
Not Available
1.57
17
Mechanical Properties
Density
Density At Room Temperature
12.41 g/cm3
28
8.79 g/cm3
99+
Density When Liquid (at m.p.)
10.70 g/cm3
14
8.34 g/cm3
26
Tensile Strength
951.00 MPa
5
Not Available
Viscosity
Not Available
Not Available
Vapor Pressure
Vapor Pressure at 1000 K
Not Available
0.00 (Pa)
16
Vapor Pressure at 2000 K
0.02 (Pa)
19
Not Available
Elasticity properties
Shear Modulus
150.00 GPa
6
26.30 GPa
28
Bulk Modulus
275.00 GPa
5
40.20 GPa
32
Young's Modulus
380.00 GPa
5
64.80 GPa
31
Poisson Ratio
0.26
22
0.23
29
Other Mechanical Properties
Malleable
Ductile, Malleable, Sectile
Magnetic Properties
Magnetic Characteristics
Specific Gravity
12.41
20
8.80
35
Magnetic Ordering
Paramagnetic
Paramagnetic
Electrical Properties
Electrical Property
Conductor
Conductor
Resistivity
43.30 nΩ·m
99+
814.00 nΩ·m
4
Electrical Conductivity
0.21 106/cm Ω
8
0.01 106/cm Ω
99+
Electron Affinity
109.70 kJ/mol
7
50.00 kJ/mol
21
Thermal Properties
Specific Heat
0.24 J/(kg K)
22
0.16 J/(kg K)
35
Molar Heat Capacity
24.98 J/mol·K
99+
27.15 J/mol·K
19
Thermal Conductivity
150.00 W/m·K
9
16.20 W/m·K
99+
Critical Temperature
Not Available
Not Available
Thermal Expansion
8.20 µm/(m·K)
99+
11.20 µm/(m·K)
35
Enthalpy
Enthalpy of Vaporization
495.40 kJ/mol
12
241.00 kJ/mol
38
Enthalpy of Fusion
21.76 kJ/mol
10
11.76 kJ/mol
29
Enthalpy of Atomization
556.50 kJ/mol
12
301.00 kJ/mol
36
Standard Molar Entropy
31.50 J/mol.K
99+
75.30 J/mol.K
8
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