91
Pa
Protactinium
231.035882
2818322092
#91
Protactinium
actinide· Solid·231.035882 u
Protactinium is a chemical element with symbol Pa and atomic number 91. It is a dense, silvery-gray metal which readily reacts with oxygen, water vapor and inorganic acids. It forms various chemical compounds where protactinium is usually present in the oxidation state +5, but can also assume +4 and even +2 or +3 states.
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Identity
- Symbol
- Pa
- Atomic Number
- 91
- Atomic Mass
- 231.035882 u
- Category
- actinide
- Block
- f-block
- Period
- 7
- Group
- 3
- Appearance
- bright, silvery metallic luster
- Year Discovered
- 1913 CE
- Discovered By
- William Crookes
- Named By
- Otto Hahn
Electrons
- Configuration
- [Rn] 5f2 6d1 7s2
- Full Configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f2 6d1
- Shells
- 2, 8, 18, 32, 20, 9, 2
- Electronegativity
- 1.5
- Electron Affinity
- 53.03
- Oxidation States
- +5, +4
- Ionization Energies
- 568
Physical Properties
- State at
- Solid
- Melting Point
- 1841
- Boiling Point
- 4300
- Density
- 15.37
- Crystal Structure
- Tetragonal
- Magnetic Ordering
- Paramagnetic
Mechanical
- Covalent Radius
- 200 pm
- Metallic Radius
- 164 pm
Thermal & Electrical
- Thermal Conductivity
- 47 W/(m K) W/(m·K)
- Specific Heat
- 120 J/(kg K) J/(g·K)
- Heat of Vaporization
- 481 kJ/mol kJ/mol
- Heat of Fusion
- 12.3 kJ/mol kJ/mol
Abundance
- Universe
- 0
- Sun
- 0
- Meteorite
- 0
- Earth's Crust
- 1.40 ppt
- Ocean
- 5e-11 ppm
- Human Body
- 0