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, which is 2 in the outermost shell.
Related: electron configuration, the Bohr model, valence electrons.
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
Protactinium: frequently asked questions
- What is Protactinium?
- Protactinium (Pa) is the chemical element with atomic number 91. It is a metal: specifically an actinide.
- What is the atomic number of Protactinium?
- Protactinium's atomic number is 91, which means every Protactinium atom has 91 protons in its nucleus.
- What is the electron configuration of Protactinium?
- The electron configuration of Protactinium is 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). Its electrons are arranged in shells of 2, 8, 18, 32, 20, 9, 2, with 2 in the outermost shell.
- Is Protactinium a metal or a nonmetal?
- Protactinium is a metal: specifically an actinide.
- What group and period is Protactinium in?
- Protactinium sits in the f-block (the actinide row) of period 7 on the periodic table.
- Is Protactinium a solid, liquid, or gas?
- At room temperature, Protactinium is a solid.
Position in the periodic table
Data compiled from Wikipedia, PubChem, and IUPAC. Source.