Symbol
Ac
Cr
Group Number
36
0
17
👆🏻
Period Number
74
2
7
👆🏻
Block
f block
d block
Element Family
Actinide
Transition Metal
CAS Number
74403487440473
7429905
54386242
👆🏻
Space Group Name
Fm_ 3m
Im_ 3m
Space Group Number
225.00229.00
11
276
👆🏻
Interesting Facts
Actinium glows in the dark due to its radioactivity.
- 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.
Sources
Obtained by Treating Radium with Neutrons, Ores of metals
Found in Minerals, Mining, Ores of metals, Ores of Minerals
History
Who Discovered
Friedrich Oskar Giesel
Louis Nicolas Vauquelin
Discovery
In 1902
In Between 1797 - 1798
Abundance
Abundance In Universe
0.00 %0.00 %
0
0.11
👆🏻
Abundance In Sun
0.00 %0.00 %
0
0.1
👆🏻
Abundance In Meteorites
0.00 %0.30 %
0
22
👆🏻
Abundance In Earth's Crust
0.00 %0.01 %
1E-37
8.1
👆🏻
Abundance In Oceans
0.00 %0.00 %
0
1.1
👆🏻
Abundance In Humans
0.00 %0.00 %
0
1.4
👆🏻
Uses & Benefits
- Actinium metal has a great source of alpha rays but it is hardly used outside research purpose.
- 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.
Industrial Uses
-
Automobile Industry, Chemical Industry
Medical Uses
-
-
Other Uses
Alloys, Nuclear Research, Research Purposes
Alloys
Biological Properties
Toxicity
Toxic
Highly Toxic
Present in Human Body
✔
✘
✔
✘
In Blood
0.00 Blood/mg dm-30.11 Blood/mg dm-3
0
1970
👆🏻
In Bone
0.00 p.p.m.0.33 p.p.m.
0
170000
👆🏻
Melting Point
1,227.00 °C1,857.00 °C
-38.83
3410
👆🏻
Boiling Point
3,200.00 °C2,672.00 °C
0
5660
👆🏻
Appearance
Physical State
Solid
Solid
Color
Silvery White
Silver
Luster
-
Metallic
Hardness
Mohs Hardness
6.508.50
0.2
8.5
👆🏻
Brinell Hardness
70.00 MPa687.00 MPa
0.14
3490
👆🏻
Vickers Hardness
260.00 MPa1,060.00 MPa
0
3920
👆🏻
Speed of Sound
3,430.00 m/s5,940.00 m/s
818
16200
👆🏻
Optical Properties
Refractive Index
1.002.97
0.155
3.41
👆🏻
Reflectivity
62.00 %70.00 %
5
97
👆🏻
Allotropes
✔
✘
✔
✘
α Allotropes
-
-
β Allotropes
-
-
γ Allotropes
-
-
Chemical Formula
Ac
Cr
Isotopes
Known Isotopes
2921
0
38
👆🏻
Electronegativity
Pauling Electronegativity
1.101.66
0
2.6
👆🏻
Sanderson Electronegativity
1.101.66
0.22
2.56
👆🏻
Allred Rochow Electronegativity
1.001.56
0.86
1.9
👆🏻
Mulliken-Jaffe Electronegativity
1.101.66
0.62
2.48
👆🏻
Allen Electronegativity
1.101.65
0.659
2.7
👆🏻
Electropositivity
Pauling Electropositivity
2.902.34
1.46
3.3
👆🏻
Ionization Energies
1st Energy Level
499.00 kJ/mol26,130.00 kJ/mol
375.7
26130
👆🏻
2nd Energy Level
1,170.00 kJ/mol28,750.00 kJ/mol
392.8
28750
👆🏻
3rd Energy Level
1,900.00 kJ/mol34,230.00 kJ/mol
392.8
34230
👆🏻
4th Energy Level
4,700.00 kJ/mol37,066.00 kJ/mol
375.7
37066
👆🏻
5th Energy Level
4,990.00 kJ/mol97,510.00 kJ/mol
392
97510
👆🏻
6th Energy Level
5,750.00 kJ/mol105,800.00 kJ/mol
1007
105800
👆🏻
7th Energy level
5,750.00 kJ/mol114,300.00 kJ/mol
1007
114300
👆🏻
8th Energy Level
5,750.00 kJ/mol125,300.00 kJ/mol
730
125300
👆🏻
9th Energy Level
4,990.00 kJ/mol134,700.00 kJ/mol
1007
134700
👆🏻
10th Energy Level
4,990.00 kJ/mol144,300.00 kJ/mol
392
144300
👆🏻
11th Energy Level
4,990.00 kJ/mol26,130.00 kJ/mol
392
169988
👆🏻
12th Energy Level
49,900.00 kJ/mol28,750.00 kJ/mol
0
189368
👆🏻
13th Energy Level
4,990.00 kJ/mol34,230.00 kJ/mol
1007
76015
👆🏻
14th Energy Level
4,990.00 kJ/mol37,066.00 kJ/mol
380
86450
👆🏻
15th Energy Level
49,900.00 kJ/mol97,510.00 kJ/mol
33000
100700
👆🏻
16th Energy Level
49,900.00 kJ/mol105,800.00 kJ/mol
375.7
109480
👆🏻
17th Energy Level
499.00 kJ/mol114,300.00 kJ/mol
375.7
122200
👆🏻
18th Energy Level
4,990.00 kJ/mol125,300.00 kJ/mol
0
134810
👆🏻
19th Energy Level
499.00 kJ/mol134,700.00 kJ/mol
375.7
148700
👆🏻
20th Energy Level
499.00 kJ/mol144,300.00 kJ/mol
0
171200
👆🏻
21st Energy Level
4,990.00 kJ/mol157,700.00 kJ/mol
375.7
179100
👆🏻
22nd Energy Level
499.00 kJ/mol166,090.00 kJ/mol
330
184900
👆🏻
23rd Energy Level
4,990.00 kJ/mol653.80 kJ/mol
357.6
198800
👆🏻
24th Energy Level
499.00 kJ/mol653.80 kJ/mol
297.3
195200
👆🏻
25th Energy Level
499.00 kJ/mol653.80 kJ/mol
0
121900
👆🏻
26th Energy Level
499.00 kJ/mol653.80 kJ/mol
357.6
127700
👆🏻
27th Energy Level
499.00 kJ/mol652.90 kJ/mol
0
133800
👆🏻
28th Energy Level
499.00 kJ/mol653.80 kJ/mol
297.3
139800
👆🏻
29th Energy Level
499.00 kJ/mol653.80 kJ/mol
0
148100
👆🏻
30th Energy Level
499.00 kJ/mol653.80 kJ/mol
0
154500
👆🏻
Electrochemical Equivalent
2.82 g/amp-hr0.32 g/amp-hr
0.16812
8.3209
👆🏻
Electron Work Function
4.38 eV4.50 eV
2.14
6
👆🏻
Other Chemical Properties
Ionization, Radioactive Isotopes, Radioactivity, Solubility
Anti Corrosion, Chemical Stability, Ionization, Radioactive Isotopes, Solubility
Atomic Number
8924
3
117
👆🏻
Electron Configuration
[Rn] 6d1 7s2
[Ar] 3d5 4s1
Crystal Structure
Face Centered Cubic (FCC)
Body Centered Cubic (BCC)
Crystal Lattice
Atom
Number of Protons
8924
3
117
👆🏻
Number of Neutrons
13828
4
285
👆🏻
Number of Electrons
8924
3
117
👆🏻
Radius of an Atom
Atomic Radius
195.00 pm128.00 pm
0
348
👆🏻
Covalent Radius
186.00 pm139.00 pm
0
260
👆🏻
Van der Waals Radius
215.00 pm200.00 pm
0
348
👆🏻
Atomic Weight
227.00 amu52.00 amu
6.94
294
👆🏻
Atomic Volume
22.54 cm3/mol7.23 cm3/mol
1.39
71.07
👆🏻
Adjacent Atomic Numbers
Previous Element
Next Element
Valence Electron Potential
38.60 (-eV)170.00 (-eV)
0
392.42
👆🏻
Lattice Constant
567.00 pm291.00 pm
0
891.25
👆🏻
Lattice Angles
π/2, π/2, π/2
π/2, π/2, π/2
Lattice C/A Ratio
1.891.86
0.423
1.9
👆🏻
Density
Density At Room Temperature
10.00 g/cm37.19 g/cm3
0.534
40.7
👆🏻
Density When Liquid (at m.p.)
10.07 g/cm36.30 g/cm3
0.512
41
👆🏻
Tensile Strength
65.00 MPa689.00 MPa
0.1
11000
👆🏻
Viscosity
0.000.00
1.5E-05
0.0035
👆🏻
Vapor Pressure
Vapor Pressure at 1000 K
0.00 (Pa)0.00 (Pa)
0
121
👆🏻
Vapor Pressure at 2000 K
0.00 (Pa)774.00 (Pa)
0
774
👆🏻
Elasticity properties
Shear Modulus
25.00 GPa115.00 GPa
1.3
222
👆🏻
Bulk Modulus
94.00 GPa160.00 GPa
0
462
👆🏻
Young's Modulus
130.00 GPa279.00 GPa
0
528
👆🏻
Poisson Ratio
0.340.21
0.032
0.47
👆🏻
Other Mechanical Properties
-
-
Magnetic Characteristics
Specific Gravity
10.077.19
0.53
4500
👆🏻
Magnetic Ordering
Paramagnetic
Antiferromagnetic
Permeability
0.00 H/m0.00 H/m
1.25643E-06
0.0063
👆🏻
Susceptibility
0.000.00
-0.000166
200000
👆🏻
Electrical Properties
Electrical Property
-
-
Resistivity
5.20 nΩ·m125.00 nΩ·m
0.1
961
👆🏻
Electrical Conductivity
0.15 106/cm Ω0.08 106/cm Ω
0
0.63
👆🏻
Electron Affinity
33.20 kJ/mol64.30 kJ/mol
0
222.8
👆🏻
Specific Heat
0.12 J/(kg K)0.45 J/(kg K)
0.1
3.6
👆🏻
Molar Heat Capacity
27.20 J/mol·K23.35 J/mol·K
13.1
62.7
👆🏻
Thermal Conductivity
12.00 W/m·K93.90 W/m·K
0
429
👆🏻
Critical Temperature
1,323.00 K1,907.00 K
26.3
3695
👆🏻
Thermal Expansion
12.10 µm/(m·K)4.90 µm/(m·K)
4.5
97
👆🏻
Enthalpy
Enthalpy of Vaporization
120.00 kJ/mol348.80 kJ/mol
7.32
799.1
👆🏻
Enthalpy of Fusion
14.20 kJ/mol15.31 kJ/mol
2.1
35.23
👆🏻
Enthalpy of Atomization
301.00 kJ/mol397.50 kJ/mol
61.5
837
👆🏻
Standard Molar Entropy
56.50 J/mol.K23.80 J/mol.K
9.5
198.1
👆🏻