Symbol
Cr
  
Al
  
Period Number
4
  
3
  
Block
d block
  
p block
  
Element Family
Transition Metal
  
Post-Transition
  
Space Group Name
Im_ 3m
  
Fm_ 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.
  
- Aluminum’s abundance percentage is more as it is found in more than 260 minerals.
- Pure Aluminum always reacts with oxygen rapidly.
- It is a good conductor of heat and electricity and used in transmission lines.
  
Sources
Found in Minerals, Mining, Ores of metals, Ores of Minerals
  
By Electrolysis Process, Earth's crust, Mining
  
History
  
  
Who Discovered
Louis Nicolas Vauquelin
  
Hans Christian Oersted
  
Discovery
In Between 1797 - 1798
  
In 1825
  
Abundance
  
  
Abundance In Universe
1.5 * 10-3 %
  
7
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.
  
- Aluminum is used in a various products; for example, cans, foils, kitchen utensils, window frames, beer kegs and aero plane parts, automobile parts, etc.
  
Industrial Uses
Automobile Industry, Chemical Industry
  
Aerospace Industry, Ammunition Industry, Automobile Industry, Chemical Industry, Electrical Industry, Electronic Industry
  
Medical Uses
NA
  
Dentistry, Pharmaceutical Industry, Surgical Instruments Manufacturing
  
Other Uses
Alloys
  
Alloys, Jewellery, Sculptures, Statues
  
Biological Properties
  
  
Toxicity
Highly Toxic
  
Non Toxic
  
Present in Human Body
Yes
  
Yes
  
In Blood
0.11 Blood/mg dm-3
  
12
0.39 Blood/mg dm-3
  
9
In Bone
0.33 p.p.m.
  
21
27.00 p.p.m.
  
11
Melting Point
1,857.00 °C
  
14
Boiling Point
2,672.00 °C
  
39
2,467.00 °C
  
99+
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Silver
  
Silvery Gray
  
Luster
Metallic
  
Metallic
  
Hardness
  
  
Brinell Hardness
160.00 MPa
  
99+
Vickers Hardness
1,060.00 MPa
  
10
Speed of Sound
5,940.00 m/s
  
5
5,000.00 m/s
  
10
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
  
Al
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Sanderson Electronegativity
Allred Rochow Electronegativity
Mulliken-Jaffe Electronegativity
Not Available
  
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
26,130.00 kJ/mol
  
1
577.50 kJ/mol
  
99+
2nd Energy Level
28,750.00 kJ/mol
  
1
1,816.70 kJ/mol
  
19
3rd Energy Level
34,230.00 kJ/mol
  
1
2,744.80 kJ/mol
  
38
4th Energy Level
37,066.00 kJ/mol
  
1
11,577.00 kJ/mol
  
3
5th Energy Level
97,510.00 kJ/mol
  
1
14,842.00 kJ/mol
  
2
6th Energy Level
105,800.00 kJ/mol
  
1
18,379.00 kJ/mol
  
2
7th Energy level
114,300.00 kJ/mol
  
1
23,326.00 kJ/mol
  
2
8th Energy Level
125,300.00 kJ/mol
  
1
27,465.00 kJ/mol
  
2
9th Energy Level
134,700.00 kJ/mol
  
1
31,853.00 kJ/mol
  
2
10th Energy Level
144,300.00 kJ/mol
  
1
38,473.00 kJ/mol
  
4
11th Energy Level
26,130.00 kJ/mol
  
12
42,647.00 kJ/mol
  
5
12th Energy Level
28,750.00 kJ/mol
  
13
Not Available
  
13th Energy Level
34,230.00 kJ/mol
  
10
Not Available
  
14th Energy Level
37,066.00 kJ/mol
  
12
Not Available
  
15th Energy Level
97,510.00 kJ/mol
  
1
Not Available
  
16th Energy Level
105,800.00 kJ/mol
  
2
Not Available
  
17th Energy Level
114,300.00 kJ/mol
  
3
Not Available
  
18th Energy Level
125,300.00 kJ/mol
  
4
Not Available
  
19th Energy Level
134,700.00 kJ/mol
  
5
Not Available
  
20th Energy Level
144,300.00 kJ/mol
  
7
Not Available
  
21st Energy Level
157,700.00 kJ/mol
  
7
Not Available
  
22nd Energy Level
166,090.00 kJ/mol
  
6
Not Available
  
Electrochemical Equivalent
0.32 g/amp-hr
  
99+
0.34 g/amp-hr
  
99+
Other Chemical Properties
Anti Corrosion, Chemical Stability, Ionization, Radioactive Isotopes, Solubility
  
Chemical Stability, Ionization, Radioactive Isotopes
  
Electron Configuration
[Ar] 3d5 4s1
  
[Ne] 3s2 3p1
  
Crystal Structure
Body Centered Cubic (BCC)
  
Face Centered Cubic (FCC)
  
Crystal Lattice
BCC-Crystal-Structure-.jpg#100
  
FCC-Crystal-Structure-of-Aluminium.jpg#100
  
Atom
  
  
Radius of an Atom
  
  
Atomic Volume
7.23 cm3/mol
  
99+
10.00 cm3/mol
  
99+
Adjacent Atomic Numbers
  
  
Valence Electron Potential
170.00 (-eV)
  
4
80.70 (-eV)
  
17
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+
2.70 g/cm3
  
99+
Density When Liquid (at m.p.)
2.38 g/cm3
  
99+
Viscosity
Not Available
  
Not Available
  
Vapor Pressure
  
  
Vapor Pressure at 2000 K
Not Available
  
Elasticity properties
  
  
Other Mechanical Properties
NA
  
Ductile, Malleable
  
Magnetic Characteristics
  
  
Magnetic Ordering
Antiferromagnetic
  
Paramagnetic
  
Permeability
Not Available
  
Susceptibility
Not Available
  
Electrical Properties
  
  
Electrical Property
NA
  
Conductor
  
Resistivity
125.00 nΩ·m
  
27
28.20 nΩ·m
  
99+
Electrical Conductivity
0.08 106/cm Ω
  
25
0.38 106/cm Ω
  
4
Electron Affinity
64.30 kJ/mol
  
15
42.50 kJ/mol
  
26
Specific Heat
0.45 J/(kg K)
  
12
0.90 J/(kg K)
  
5
Molar Heat Capacity
23.35 J/mol·K
  
99+
24.20 J/mol·K
  
99+
Thermal Conductivity
93.90 W/m·K
  
17
237.00 W/m·K
  
4
Critical Temperature
Not Available
  
Not Available
  
Thermal Expansion
4.90 µm/(m·K)
  
99+
23.10 µm/(m·K)
  
17
Enthalpy
  
  
Enthalpy of Vaporization
348.80 kJ/mol
  
24
293.70 kJ/mol
  
31
Enthalpy of Fusion
15.31 kJ/mol
  
20
10.67 kJ/mol
  
35
Enthalpy of Atomization
397.50 kJ/mol
  
21
322.20 kJ/mol
  
31
Standard Molar Entropy
23.80 J/mol.K
  
99+
28.30 J/mol.K
  
99+