Symbol
Cr
  
Mo
  
Period Number
4
  
5
  
Block
d block
  
d block
  
Element Family
Transition Metal
  
Transition Metal
  
Space Group Name
Im_ 3m
  
Im_ 3m
  
Interesting Facts
- Chromium is highly reactive, hence it is not found free in nature.
- Ores of Chromites mineral are the major source of Chromium metal.
- Almost 90% leather tanning is done with the help of chromium.
  
- Molybdenum is highly reactive metal, hence not found free in nature .
- Till 18th century Molybdenum element were often mistaken as a carbon or Lead.
  
Sources
Found in Minerals, Mining, Ores of metals, Ores of Minerals
  
Found in Minerals, Mining, Ores of Minerals
  
History
  
  
Who Discovered
Louis Nicolas Vauquelin
  
Carl Wilhelm Scheele
  
Discovery
In Between 1797 - 1798
  
In 1778
  
Abundance
  
  
Abundance In Universe
1.5 * 10-3 %
  
7
Abundance In Sun
~0.0000009 %
  
19
Abundance In Earth's Crust
Uses & Benefits
- It is used to harden the steel and produces a stainless steel and other various alloys.
- It is also used to give proper finish to polished mirrors. Its chromium plates are used in bathroom fittings.
  
- 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.
  
Industrial Uses
Automobile Industry, Chemical Industry
  
Aerospace Industry, Electrical Industry, Electronic Industry
  
Medical Uses
NA
  
NA
  
Other Uses
Alloys
  
Alloys
  
Biological Properties
  
  
Toxicity
Highly Toxic
  
Toxic
  
Present in Human Body
Yes
  
Yes
  
In Blood
0.11 Blood/mg dm-3
  
12
0.00 Blood/mg dm-3
  
31
In Bone
0.33 p.p.m.
  
21
0.70 p.p.m.
  
18
Melting Point
1,857.00 °C
  
14
Boiling Point
2,672.00 °C
  
39
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Silver
  
Gray
  
Luster
Metallic
  
Metallic
  
Hardness
  
  
Brinell Hardness
1,370.00 MPa
  
7
Vickers Hardness
1,060.00 MPa
  
10
1,400.00 MPa
  
6
Speed of Sound
5,940.00 m/s
  
5
5,400.00 m/s
  
6
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
Cr
  
Mo
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Sanderson Electronegativity
Allred Rochow Electronegativity
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
26,130.00 kJ/mol
  
1
684.30 kJ/mol
  
37
2nd Energy Level
28,750.00 kJ/mol
  
1
1,560.00 kJ/mol
  
37
3rd Energy Level
34,230.00 kJ/mol
  
1
2,618.00 kJ/mol
  
99+
4th Energy Level
37,066.00 kJ/mol
  
1
4,480.00 kJ/mol
  
26
5th Energy Level
97,510.00 kJ/mol
  
1
5,257.00 kJ/mol
  
32
6th Energy Level
105,800.00 kJ/mol
  
1
6,640.80 kJ/mol
  
22
7th Energy level
114,300.00 kJ/mol
  
1
12,125.00 kJ/mol
  
13
8th Energy Level
125,300.00 kJ/mol
  
1
13,860.00 kJ/mol
  
16
9th Energy Level
134,700.00 kJ/mol
  
1
15,835.00 kJ/mol
  
16
10th Energy Level
144,300.00 kJ/mol
  
1
17,980.00 kJ/mol
  
18
11th Energy Level
26,130.00 kJ/mol
  
12
20,190.00 kJ/mol
  
17
12th Energy Level
28,750.00 kJ/mol
  
13
22,219.00 kJ/mol
  
15
13th Energy Level
34,230.00 kJ/mol
  
10
26,930.00 kJ/mol
  
13
14th Energy Level
37,066.00 kJ/mol
  
12
29,196.00 kJ/mol
  
13
15th Energy Level
97,510.00 kJ/mol
  
1
52,490.00 kJ/mol
  
7
16th Energy Level
105,800.00 kJ/mol
  
2
55,000.00 kJ/mol
  
8
17th Energy Level
114,300.00 kJ/mol
  
3
61,400.00 kJ/mol
  
9
18th Energy Level
125,300.00 kJ/mol
  
4
67,700.00 kJ/mol
  
9
19th Energy Level
134,700.00 kJ/mol
  
5
74,000.00 kJ/mol
  
9
20th Energy Level
144,300.00 kJ/mol
  
7
80,400.00 kJ/mol
  
10
21st Energy Level
157,700.00 kJ/mol
  
7
87,000.00 kJ/mol
  
9
22nd Energy Level
166,090.00 kJ/mol
  
6
93,400.00 kJ/mol
  
7
23rd Energy Level
Not Available
  
98,420.00 kJ/mol
  
6
24th Energy Level
Not Available
  
104,400.00 kJ/mol
  
2
25th Energy Level
Not Available
  
121,900.00 kJ/mol
  
1
26th Energy Level
Not Available
  
127,700.00 kJ/mol
  
1
27th Energy Level
Not Available
  
133,800.00 kJ/mol
  
1
28th Energy Level
Not Available
  
139,800.00 kJ/mol
  
1
29th Energy Level
Not Available
  
148,100.00 kJ/mol
  
1
30th Energy Level
Not Available
  
154,500.00 kJ/mol
  
1
Electrochemical Equivalent
0.32 g/amp-hr
  
99+
0.89 g/amp-hr
  
99+
Other Chemical Properties
Anti Corrosion, Chemical Stability, Ionization, Radioactive Isotopes, Solubility
  
Anti Corrosion, Ionization, Radioactive Isotopes, Solubility
  
Electron Configuration
[Ar] 3d5 4s1
  
[Kr] 4d5 5s1
  
Crystal Structure
Body Centered Cubic (BCC)
  
Body Centered Cubic (BCC)
  
Crystal Lattice
BCC-Crystal-Structure-.jpg#100
  
BCC-Crystal-Structure-.jpg#100
  
Atom
  
  
Radius of an Atom
  
  
Atomic Volume
7.23 cm3/mol
  
99+
9.40 cm3/mol
  
99+
Adjacent Atomic Numbers
  
  
Valence Electron Potential
170.00 (-eV)
  
4
88.60 (-eV)
  
13
Lattice Angles
π/2, π/2, π/2
  
π/2, π/2, π/2
  
Lattice C/A Ratio
Not Available
  
Not Available
  
Density
  
  
Density At Room Temperature
7.19 g/cm3
  
99+
10.28 g/cm3
  
36
Density When Liquid (at m.p.)
Viscosity
Not Available
  
Not Available
  
Vapor Pressure
  
  
Vapor Pressure at 1000 K
Not Available
  
Elasticity properties
  
  
Other Mechanical Properties
NA
  
Ductile, Weldable
  
Magnetic Characteristics
  
  
Magnetic Ordering
Antiferromagnetic
  
Paramagnetic
  
Electrical Properties
  
  
Electrical Property
NA
  
Semiconductor
  
Resistivity
125.00 nΩ·m
  
27
53.40 nΩ·m
  
99+
Electrical Conductivity
0.08 106/cm Ω
  
25
0.19 106/cm Ω
  
11
Electron Affinity
64.30 kJ/mol
  
15
71.90 kJ/mol
  
14
Specific Heat
0.45 J/(kg K)
  
12
0.25 J/(kg K)
  
21
Molar Heat Capacity
23.35 J/mol·K
  
99+
24.06 J/mol·K
  
99+
Thermal Conductivity
93.90 W/m·K
  
17
138.00 W/m·K
  
12
Critical Temperature
Not Available
  
Not Available
  
Thermal Expansion
4.90 µm/(m·K)
  
99+
4.80 µm/(m·K)
  
99+
Enthalpy
  
  
Enthalpy of Vaporization
348.80 kJ/mol
  
24
594.10 kJ/mol
  
8
Enthalpy of Fusion
15.31 kJ/mol
  
20
27.61 kJ/mol
  
5
Enthalpy of Atomization
397.50 kJ/mol
  
21
653.00 kJ/mol
  
7
Standard Molar Entropy
23.80 J/mol.K
  
99+
28.70 J/mol.K
  
99+