91 Pa 231.036
Protactinium
actinide
Properties
- Atomic number
- 91
- Atomic mass
- 231.036 u
- Category
- actinide
- Group
- f-block
- Period
- 7
- Block
- f-block
- State (room temp)
- Solid
- Outer-shell electrons
- 2
- Electronegativity
- 1.5 (Pauling)
- Density
- 15.37 g/cm³
- Melting point
- 1567.85 °C
- Boiling point
- 4026.85 °C
Electron configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f² 6d¹
Noble-gas shorthand: [Rn] 5f² 6d¹ 7s²
Electrons per shell: 2, 8, 18, 32, 20, 9, 2 — that's 2 in the outermost shell.
About Protactinium
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.
- Discovered by William Crookes
- Named by Otto Hahn
- Appearance: bright, silvery metallic luster
Position in the periodic table
Data compiled from Wikipedia, PubChem, and IUPAC. Source.