89 Ac 227
Actinium
actinide
Properties
- Atomic number
- 89
- Atomic mass
- 227 u
- Category
- actinide
- Group
- f-block
- Period
- 7
- Block
- f-block
- State (room temp)
- Solid
- Outer-shell electrons
- 2
- Electronegativity
- 1.1 (Pauling)
- Density
- 10 g/cm³
- Melting point
- 1226.85 °C
- Boiling point
- 3226.85 °C
Electron configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 6d¹
Noble-gas shorthand: [Rn] 6d¹ 7s²
Electrons per shell: 2, 8, 18, 32, 18, 9, 2, which is 2 in the outermost shell.
Related: electron configuration, the Bohr model, valence electrons.
About Actinium
Actinium is a radioactive chemical element with symbol Ac (not to be confused with the abbreviation for an acetyl group) and atomic number 89, which was discovered in 1899. It was the first non-primordial radioactive element to be isolated. Polonium, radium and radon were observed before actinium, but they were not isolated until 1902.
- Discovered by Friedrich Oskar Giesel
Actinium: frequently asked questions
- What is Actinium?
- Actinium (Ac) is the chemical element with atomic number 89. It is a metal: specifically an actinide.
- What is the atomic number of Actinium?
- Actinium's atomic number is 89, which means every Actinium atom has 89 protons in its nucleus.
- What is the electron configuration of Actinium?
- The electron configuration of Actinium is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 6d1 (noble-gas shorthand: [Rn] 6d1 7s2). Its electrons are arranged in shells of 2, 8, 18, 32, 18, 9, 2, with 2 in the outermost shell.
- Is Actinium a metal or a nonmetal?
- Actinium is a metal: specifically an actinide.
- What group and period is Actinium in?
- Actinium sits in the f-block (the actinide row) of period 7 on the periodic table.
- Is Actinium a solid, liquid, or gas?
- At room temperature, Actinium is a solid.
Position in the periodic table
Data compiled from Wikipedia, PubChem, and IUPAC. Source.