Symbol
Hf
  
Pa
  
Group Number
Not Available
  
Period Number
6
  
7
  
Block
d block
  
f block
  
Element Family
Transition Metal
  
Actinide
  
Space Group Name
P63/mmc
  
I4/mmm
  
Interesting Facts
- Hafnium metal is highly reactive, hence not found free in nature.
- Hafnium metal as predicated after Mendeleev finished his periodic table.
  
- Protactinium metal has 29 isotopes.
- Isotopes of Protactinium-231 used in nuclear weapon.
  
Sources
By-product Zirconium Refining
  
Found in Uranium Ores, Mining, Ores of metals
  
History
  
  
Who Discovered
Dirk Coster and George de Hevesy
  
William Crookes
  
Discovery
In 1922
  
In 1900
  
Abundance
  
  
Abundance In Universe
Not Available
  
Abundance In Sun
~0.0000001 %
  
26
~-9999 %
  
Abundance In Meteorites
Not Available
  
Abundance In Earth's Crust
Uses & Benefits
- 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.
  
- Currently known uses of Protactinium metal are limited to research purpose only.
  
Industrial Uses
Ammunition Industry
  
NA
  
Medical Uses
NA
  
NA
  
Other Uses
Alloys, In Nuclear Reactors, Nuclear Research, Research Purposes
  
NA
  
Biological Properties
  
  
Toxicity
Toxic
  
Highly Toxic
  
Present in Human Body
No
  
No
  
In Blood
Not Available
  
0.00 Blood/mg dm-3
  
37
In Bone
Not Available
  
0.00 p.p.m.
  
36
Melting Point
2,150.00 °C
  
10
1,568.00 °C
  
21
Boiling Point
4,027.00 °C
  
12
Appearance
  
  
Physical State
Solid
  
Solid
  
Color
Gray
  
Silver
  
Luster
Metallic
  
Metallic
  
Hardness
  
  
Mohs Hardness
Not Available
  
Brinell Hardness
1,450.00 MPa
  
6
Not Available
  
Vickers Hardness
1,520.00 MPa
  
5
Not Available
  
Speed of Sound
3,010.00 m/s
  
27
Not Available
  
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
Hf
  
Pa
  
Isotopes
  
  
Electronegativity
  
  
Pauling Electronegativity
Allred Rochow Electronegativity
Allen Electronegativity
Not Available
  
Electropositivity
  
  
Pauling Electropositivity
Ionization Energies
  
  
1st Energy Level
658.50 kJ/mol
  
40
568.00 kJ/mol
  
99+
2nd Energy Level
1,440.00 kJ/mol
  
99+
1,128.00 kJ/mol
  
99+
3rd Energy Level
2,250.00 kJ/mol
  
99+
1,814.00 kJ/mol
  
99+
4th Energy Level
3,216.00 kJ/mol
  
99+
2,991.00 kJ/mol
  
99+
Electrochemical Equivalent
1.66 g/amp-hr
  
99+
1.72 g/amp-hr
  
99+
Electron Work Function
Not Available
  
Other Chemical Properties
Anti Corrosion, Ionization, Radioactive Isotopes, Solubility
  
Ionization, Radioactive Isotopes, Radioactivity
  
Electron Configuration
[Xe] 4f14 5d2 6s2
  
[Rn] 5f2 6d1 7s2
  
Crystal Structure
Hexagonal Close Packed (HCP)
  
Tetragonal (TETR)
  
Crystal Lattice
BCC-Crystal-Structure-.jpg#100
  
TETR-Crystal-Structure-of-Protactinium.jpg#100
  
Atom
  
  
Radius of an Atom
  
  
Atomic Volume
13.60 cm3/mol
  
38
15.00 cm3/mol
  
34
Adjacent Atomic Numbers
  
  
Valence Electron Potential
81.00 (-eV)
  
16
92.00 (-eV)
  
11
Lattice Angles
π/2, π/2, 2 π/3
  
π/2, π/2, π/2
  
Lattice C/A Ratio
Not Available
  
Density
  
  
Density At Room Temperature
13.31 g/cm3
  
26
15.37 g/cm3
  
20
Density When Liquid (at m.p.)
12.00 g/cm3
  
12
Not Available
  
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
Ductile, Malleable
  
Unknown
  
Magnetic Characteristics
  
  
Magnetic Ordering
Paramagnetic
  
Paramagnetic
  
Electrical Properties
  
  
Electrical Property
Conductor
  
Conductor
  
Resistivity
331.00 nΩ·m
  
14
177.00 nΩ·m
  
21
Electrical Conductivity
0.03 106/cm Ω
  
39
0.05 106/cm Ω
  
34
Electron Affinity
0.00 kJ/mol
  
40
Not Available
  
Specific Heat
0.14 J/(kg K)
  
37
0.12 J/(kg K)
  
40
Molar Heat Capacity
25.73 J/mol·K
  
36
Not Available
  
Thermal Conductivity
23.00 W/m·K
  
99+
47.00 W/m·K
  
32
Critical Temperature
Not Available
  
Not Available
  
Thermal Expansion
5.90 µm/(m·K)
  
99+
9.90 µm/(m·K)
  
40
Enthalpy
  
  
Enthalpy of Vaporization
661.10 kJ/mol
  
5
Not Available
  
Enthalpy of Fusion
25.10 kJ/mol
  
8
12.34 kJ/mol
  
28
Enthalpy of Atomization
703.00 kJ/mol
  
5
Not Available
  
Standard Molar Entropy
43.60 J/mol.K
  
34
198.10 J/mol.K
  
1