Symbol
Ac
  
Hf
  
Group Number
Not Available
  
Period Number
7
  
6
  
Block
f block
  
d block
  
Element Family
Actinide
  
Transition Metal
  
Space Group Name
Fm_ 3m
  
P63/mmc
  
Interesting Facts
Not Available
  
- Hafnium metal is highly reactive, hence not found free in nature.
- Hafnium metal as predicated after Mendeleev finished his periodic table.
  
Sources
Obtained by Treating Radium with Neutrons, Ores of metals
  
By-product Zirconium Refining
  
History
  
  
Who Discovered
Friedrich Oskar Giesel
  
Dirk Coster and George de Hevesy
  
Discovery
In 1902
  
In 1922
  
Abundance
  
  
Abundance In Universe
Not Available
  
Abundance In Sun
~-9999 %
  
~0.0000001 %
  
26
Abundance In Meteorites
Not Available
  
Abundance In Earth's Crust
Not Available
  
Abundance In Oceans
Not Available
  
Uses & Benefits
- Actinium metal has a great source of alpha rays but it is hardly used outside research purpose.
  
- 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
NA
  
Ammunition Industry
  
Medical Uses
NA
  
NA
  
Other Uses
Alloys, Nuclear Research, Research Purposes
  
Alloys, In Nuclear Reactors, Nuclear Research, Research Purposes
  
Biological Properties
  
  
Toxicity
Toxic
  
Toxic
  
Present in Human Body
No
  
No
  
In Blood
0.00 Blood/mg dm-3
  
37
Not Available
  
In Bone
0.00 p.p.m.
  
36
Not Available
  
Melting Point
1,227.00 °C
  
38
2,150.00 °C
  
10
Boiling Point
3,200.00 °C
  
26
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Silvery White
  
Gray
  
Luster
NA
  
Metallic
  
Hardness
  
  
Mohs Hardness
Not Available
  
Brinell Hardness
Not Available
  
1,450.00 MPa
  
6
Vickers Hardness
Not Available
  
1,520.00 MPa
  
5
Speed of Sound
Not Available
  
3,010.00 m/s
  
27
Optical Properties
  
  
Allotropes
No
  
No
  
α Allotropes
Not Available
  
Not Available
  
β Allotropes
Not Available
  
Not Available
  
γ Allotropes
Not Available
  
Not Available
  
Chemical Formula
Ac
  
Hf
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Allred Rochow Electronegativity
Allen Electronegativity
Not Available
  
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
499.00 kJ/mol
  
99+
658.50 kJ/mol
  
40
2nd Energy Level
1,170.00 kJ/mol
  
99+
1,440.00 kJ/mol
  
99+
3rd Energy Level
1,900.00 kJ/mol
  
99+
2,250.00 kJ/mol
  
99+
4th Energy Level
4,700.00 kJ/mol
  
23
3,216.00 kJ/mol
  
99+
Electrochemical Equivalent
2.82 g/amp-hr
  
18
1.66 g/amp-hr
  
99+
Electron Work Function
Not Available
  
Other Chemical Properties
Ionization, Radioactive Isotopes, Radioactivity, Solubility
  
Anti Corrosion, Ionization, Radioactive Isotopes, Solubility
  
Electron Configuration
[Rn] 6d1 7s2
  
[Xe] 4f14 5d2 6s2
  
Crystal Structure
Face Centered Cubic (FCC)
  
Hexagonal Close Packed (HCP)
  
Crystal Lattice
FCC-Crystal-Structure-of-Actinium.jpg#100
  
BCC-Crystal-Structure-.jpg#100
  
Atom
  
  
Radius of an Atom
  
  
Covalent Radius
Not Available
  
Van der Waals Radius
Not Available
  
Atomic Volume
22.54 cm3/mol
  
11
13.60 cm3/mol
  
38
Adjacent Atomic Numbers
  
  
Valence Electron Potential
38.60 (-eV)
  
99+
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
10.00 g/cm3
  
37
13.31 g/cm3
  
26
Density When Liquid (at m.p.)
Not Available
  
12.00 g/cm3
  
12
Tensile Strength
Not Available
  
Viscosity
Not Available
  
Not Available
  
Vapor Pressure
  
  
Vapor Pressure at 2000 K
Not Available
  
Elasticity properties
  
  
Shear Modulus
Not Available
  
Bulk Modulus
Not Available
  
Young's Modulus
Not Available
  
Poisson Ratio
Not Available
  
Other Mechanical Properties
NA
  
Ductile, Malleable
  
Magnetic Characteristics
  
  
Magnetic Ordering
Paramagnetic
  
Paramagnetic
  
Electrical Properties
  
  
Electrical Property
Unknown
  
Conductor
  
Resistivity
Not Available
  
331.00 nΩ·m
  
14
Electrical Conductivity
Not Available
  
0.03 10
6/cm Ω
  
39
Electron Affinity
Not Available
  
0.00 kJ/mol
  
40
Specific Heat
0.12 J/(kg K)
  
40
0.14 J/(kg K)
  
37
Molar Heat Capacity
27.20 J/mol·K
  
18
25.73 J/mol·K
  
36
Thermal Conductivity
12.00 W/m·K
  
99+
23.00 W/m·K
  
99+
Critical Temperature
Not Available
  
Not Available
  
Thermal Expansion
Not Available
  
5.90 µm/(m·K)
  
99+
Enthalpy
  
  
Enthalpy of Vaporization
Not Available
  
661.10 kJ/mol
  
5
Enthalpy of Fusion
Not Available
  
25.10 kJ/mol
  
8
Enthalpy of Atomization
301.00 kJ/mol
  
36
703.00 kJ/mol
  
5
Standard Molar Entropy
56.50 J/mol.K
  
25
43.60 J/mol.K
  
34