Protactinium Neptunium Comparison
Periodic Table
Symbol
Pa
Np
Group Number
Not Available
Not Available
Period Number
7
7
Block
f block
f block
Element Family
Actinide
Actinide
CAS Number
7440133
99+
7439998
99+
Space Group Name
I4/mmm
Pnma
Space Group Number
139.00
8
62.00
11
Facts
Interesting Facts
- Protactinium metal has 29 isotopes.
- Isotopes of Protactinium-231 used in nuclear weapon.
Not Available
Sources
Found in Uranium Ores, Mining, Ores of metals
Made by Bombarding Uranium with Neutrons, Ores of metals
History
Who Discovered
William Crookes
Edwin McMillan and Philip H. Abelson
Discovery
In 1900
In 1940
Abundance
Abundance In Earth's Crust
0.00 %
99+
Not Available
Abundance In Oceans
0.00 %
99+
Not Available
Uses
Uses & Benefits
- Currently known uses of Protactinium metal are limited to research purpose only.
- Currently known uses of Neptunium metal are limited to research purpose only.
- Neptunium’s isotope neptunium-237 is used as a neutron detectors.
Industrial Uses
NA
NA
Medical Uses
NA
NA
Other Uses
NA
Alloys, Nuclear Research, Research Purposes
Biological Properties
Toxicity
Highly Toxic
Toxic
Present in Human Body
No
No
In Blood
0.00 Blood/mg dm-3
37
0.00 Blood/mg dm-3
37
In Bone
0.00 p.p.m.
36
0.00 p.p.m.
36
Physical Properties
Melting Point
1,568.00 °C
21
640.00 °C
99+
Boiling Point
4,027.00 °C
12
3,902.00 °C
13
Appearance
Physical State
Solid
Solid
Color
Silver
Silver
Luster
Metallic
Metallic
Hardness
Speed of Sound
Not Available
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 Properties
Chemical Formula
Pa
Np
Isotopes
Known Isotopes
27
12
20
19
Electronegativity
Pauling Electronegativity
1.50
27
1.36
29
Allred Rochow Electronegativity
1.14
28
1.22
26
Electropositivity
Pauling Electropositivity
2.50
27
2.64
25
Ionization Energies
1st Energy Level
568.00 kJ/mol
99+
604.50 kJ/mol
99+
2nd Energy Level
1,128.00 kJ/mol
99+
1,128.00 kJ/mol
99+
3rd Energy Level
1,814.00 kJ/mol
99+
1,997.00 kJ/mol
99+
4th Energy Level
2,991.00 kJ/mol
99+
3,242.00 kJ/mol
99+
Electrochemical Equivalent
1.72 g/amp-hr
99+
1.77 g/amp-hr
39
Electron Work Function
Not Available
Not Available
Other Chemical Properties
Ionization, Radioactive Isotopes, Radioactivity
Ionization, Radioactive Isotopes, Radioactivity, Solubility
Atomic Properties
Atomic Number
91
27
93
25
Electron Configuration
[Rn] 5f2 6d1 7s2
[Rn] 5f4 6d1 7s2
Crystal Structure
Tetragonal (TETR)
Orthorhombic (ORTH)
Crystal Lattice
TETR-Crystal-Structure-of-Protactinium.jpg#100
ORTH-Crystal-Structure-of-Neptunium.jpg#100
Atom
Number of Protons
91
27
93
25
Number of Neutrons
122
21
144
14
Number of Electrons
91
27
93
25
Radius of an Atom
Atomic Radius
163.00 pm
25
155.00 pm
30
Covalent Radius
200.00 pm
11
190.00 pm
18
Van der Waals Radius
243.00 pm
11
221.00 pm
22
Atomic Weight
231.04 amu
24
237.00 amu
22
Atomic Volume
15.00 cm3/mol
34
11.62 cm3/mol
99+
Adjacent Atomic Numbers
Valence Electron Potential
92.00 (-eV)
11
96.00 (-eV)
9
Lattice Constant
392.50 pm
23
666.30 pm
3
Lattice Angles
π/2, π/2, π/2
π/2, π/2, π/2
Lattice C/A Ratio
Not Available
Not Available
Mechanical Properties
Density
Density At Room Temperature
15.37 g/cm3
20
19.38 g/cm3
14
Tensile Strength
Not Available
125.00 MPa
14
Viscosity
Not Available
Not Available
Vapor Pressure
Vapor Pressure at 2000 K
Not Available
0.11 (Pa)
17
Elasticity properties
Poisson Ratio
Not Available
Not Available
Other Mechanical Properties
Unknown
Ductile
Magnetic Properties
Magnetic Characteristics
Specific Gravity
15.37
12
20.25
6
Magnetic Ordering
Paramagnetic
Paramagnetic
Electrical Properties
Electrical Property
Conductor
Conductor
Resistivity
177.00 nΩ·m
21
1.22 nΩ·m
99+
Electrical Conductivity
0.05 106/cm Ω
34
0.01 106/cm Ω
99+
Thermal Properties
Specific Heat
0.12 J/(kg K)
40
0.12 J/(kg K)
40
Molar Heat Capacity
Not Available
29.46 J/mol·K
8
Thermal Conductivity
47.00 W/m·K
32
6.30 W/m·K
99+
Critical Temperature
Not Available
Not Available
Thermal Expansion
9.90 µm/(m·K)
40
Not Available
Enthalpy
Enthalpy of Fusion
12.34 kJ/mol
28
3.20 kJ/mol
99+
Standard Molar Entropy
198.10 J/mol.K
1
Not Available
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