Symbol
Mo
  
Hf
  
Period Number
5
  
6
  
Block
d block
  
d block
  
Element Family
Transition Metal
  
Transition Metal
  
Space Group Name
Im_ 3m
  
P63/mmc
  
Interesting Facts
- Molybdenum is highly reactive metal, hence not found free in nature .
- Till 18th century Molybdenum element were often mistaken as a carbon or Lead.
  
- Hafnium metal is highly reactive, hence not found free in nature.
- Hafnium metal as predicated after Mendeleev finished his periodic table.
  
Sources
Found in Minerals, Mining, Ores of Minerals
  
By-product Zirconium Refining
  
History
  
  
Who Discovered
Carl Wilhelm Scheele
  
Dirk Coster and George de Hevesy
  
Discovery
In 1778
  
In 1922
  
Abundance
  
  
Abundance In Sun
~0.0000009 %
  
19
~0.0000001 %
  
26
Abundance In Earth's Crust
Abundance In Humans
Not Available
  
Uses & Benefits
- Its alloys are used to make engine parts, drills, saw blade, etc.
- Lubricant additive made up of Molybdenum disulfide is commonly used in the industry. It is also used as a catalyst.
  
- 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.
  
Industrial Uses
Aerospace Industry, Electrical Industry, Electronic Industry
  
Ammunition Industry
  
Medical Uses
NA
  
NA
  
Other Uses
Alloys
  
Alloys, In Nuclear Reactors, Nuclear Research, Research Purposes
  
Biological Properties
  
  
Toxicity
Toxic
  
Toxic
  
Present in Human Body
Yes
  
No
  
In Blood
0.00 Blood/mg dm-3
  
31
Not Available
  
In Bone
0.70 p.p.m.
  
18
Not Available
  
Melting Point
2,150.00 °C
  
10
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Gray
  
Gray
  
Luster
Metallic
  
Metallic
  
Hardness
  
  
Brinell Hardness
1,370.00 MPa
  
7
1,450.00 MPa
  
6
Vickers Hardness
1,400.00 MPa
  
6
1,520.00 MPa
  
5
Speed of Sound
5,400.00 m/s
  
6
3,010.00 m/s
  
27
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
Mo
  
Hf
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Sanderson Electronegativity
Not Available
  
Allred Rochow Electronegativity
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
684.30 kJ/mol
  
37
658.50 kJ/mol
  
40
2nd Energy Level
1,560.00 kJ/mol
  
37
1,440.00 kJ/mol
  
99+
3rd Energy Level
2,618.00 kJ/mol
  
99+
2,250.00 kJ/mol
  
99+
4th Energy Level
4,480.00 kJ/mol
  
26
3,216.00 kJ/mol
  
99+
5th Energy Level
5,257.00 kJ/mol
  
32
Not Available
  
6th Energy Level
6,640.80 kJ/mol
  
22
Not Available
  
7th Energy level
12,125.00 kJ/mol
  
13
Not Available
  
8th Energy Level
13,860.00 kJ/mol
  
16
Not Available
  
9th Energy Level
15,835.00 kJ/mol
  
16
Not Available
  
10th Energy Level
17,980.00 kJ/mol
  
18
Not Available
  
11th Energy Level
20,190.00 kJ/mol
  
17
Not Available
  
12th Energy Level
22,219.00 kJ/mol
  
15
Not Available
  
13th Energy Level
26,930.00 kJ/mol
  
13
Not Available
  
14th Energy Level
29,196.00 kJ/mol
  
13
Not Available
  
15th Energy Level
52,490.00 kJ/mol
  
7
Not Available
  
16th Energy Level
55,000.00 kJ/mol
  
8
Not Available
  
17th Energy Level
61,400.00 kJ/mol
  
9
Not Available
  
18th Energy Level
67,700.00 kJ/mol
  
9
Not Available
  
19th Energy Level
74,000.00 kJ/mol
  
9
Not Available
  
20th Energy Level
80,400.00 kJ/mol
  
10
Not Available
  
21st Energy Level
87,000.00 kJ/mol
  
9
Not Available
  
22nd Energy Level
93,400.00 kJ/mol
  
7
Not Available
  
23rd Energy Level
98,420.00 kJ/mol
  
6
Not Available
  
24th Energy Level
104,400.00 kJ/mol
  
2
Not Available
  
25th Energy Level
121,900.00 kJ/mol
  
1
Not Available
  
26th Energy Level
127,700.00 kJ/mol
  
1
Not Available
  
27th Energy Level
133,800.00 kJ/mol
  
1
Not Available
  
28th Energy Level
139,800.00 kJ/mol
  
1
Not Available
  
29th Energy Level
148,100.00 kJ/mol
  
1
Not Available
  
30th Energy Level
154,500.00 kJ/mol
  
1
Not Available
  
Electrochemical Equivalent
0.89 g/amp-hr
  
99+
1.66 g/amp-hr
  
99+
Other Chemical Properties
Anti Corrosion, Ionization, Radioactive Isotopes, Solubility
  
Anti Corrosion, Ionization, Radioactive Isotopes, Solubility
  
Electron Configuration
[Kr] 4d5 5s1
  
[Xe] 4f14 5d2 6s2
  
Crystal Structure
Body Centered Cubic (BCC)
  
Hexagonal Close Packed (HCP)
  
Crystal Lattice
BCC-Crystal-Structure-.jpg#100
  
BCC-Crystal-Structure-.jpg#100
  
Atom
  
  
Radius of an Atom
  
  
Atomic Volume
9.40 cm3/mol
  
99+
13.60 cm3/mol
  
38
Adjacent Atomic Numbers
  
  
Valence Electron Potential
88.60 (-eV)
  
13
81.00 (-eV)
  
16
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
10.28 g/cm3
  
36
13.31 g/cm3
  
26
Density When Liquid (at m.p.)
12.00 g/cm3
  
12
Viscosity
Not Available
  
Not Available
  
Vapor Pressure
  
  
Elasticity properties
  
  
Other Mechanical Properties
Ductile, Weldable
  
Ductile, Malleable
  
Magnetic Characteristics
  
  
Magnetic Ordering
Paramagnetic
  
Paramagnetic
  
Electrical Properties
  
  
Electrical Property
Semiconductor
  
Conductor
  
Resistivity
53.40 nΩ·m
  
99+
331.00 nΩ·m
  
14
Electrical Conductivity
0.19 106/cm Ω
  
11
0.03 106/cm Ω
  
39
Electron Affinity
71.90 kJ/mol
  
14
0.00 kJ/mol
  
40
Specific Heat
0.25 J/(kg K)
  
21
0.14 J/(kg K)
  
37
Molar Heat Capacity
24.06 J/mol·K
  
99+
25.73 J/mol·K
  
36
Thermal Conductivity
138.00 W/m·K
  
12
23.00 W/m·K
  
99+
Critical Temperature
Not Available
  
Not Available
  
Thermal Expansion
4.80 µm/(m·K)
  
99+
5.90 µm/(m·K)
  
99+
Enthalpy
  
  
Enthalpy of Vaporization
594.10 kJ/mol
  
8
661.10 kJ/mol
  
5
Enthalpy of Fusion
27.61 kJ/mol
  
5
25.10 kJ/mol
  
8
Enthalpy of Atomization
653.00 kJ/mol
  
7
703.00 kJ/mol
  
5
Standard Molar Entropy
28.70 J/mol.K
  
99+
43.60 J/mol.K
  
34