Actinium
Actinium (锕, symbol Ac) is chemical element number 89, an Actinide in period 7, group 3 of the periodic table, with a standard atomic weight of about 227. Soft, silvery-white radioactive metal that glows pale blue in the dark.
Properties
| Atomic number | 89 |
|---|---|
| Symbol | Ac |
| Atomic mass | 227 u |
| Category | Actinide |
| Period | 7 |
| Group | 3 |
| Electron configuration | [Rn] 6d¹ 7s² |
| Electronegativity | 1.1 |
| Covalent radius | 215 pm |
| Density | 10.07 g/cm³ |
| Melting point | 1323 K |
| Boiling point | 3471 K |
| Discovery | André-Louis Debierne, 1899 |
Overview
Soft, silvery-white radioactive metal that glows pale blue in the dark. Element 89, Actinium (Ac), is an Actinide found in period 7, group 3. As an actinide it is typically radioactive and closely tied to nuclear technology.
Its electron configuration is [Rn] 6d¹ 7s², with 2 electrons in the outer shell, and an electronegativity of about 1.1 (Pauling). Around 25 °C it is usually a solid; it melts near 1323 K (1049.9 °C), boils near 3471 K (3197.9 °C), has a density around 10.07 g/cm³.
In industry and daily life it turns up in Medical / Pharma and Research. On the safety side, it carries a high hazard rating. It was first described by André-Louis Debierne in 1899. The periodic trends guide explains the underlying patterns.
Electron shells
Electrons per shell: 2 · 8 · 18 · 32 · 18 · 9 · 2
Main uses
- Medical / Pharma
- Research
Hazard
Compounds containing Actinium
No compounds in this knowledge base contain Actinium yet.
Data sources
Atomic mass uses IUPAC (CIAAW) standard atomic weights; the covalent radius is from Cordero et al. (2008). Verify on the RSC Periodic Table, PubChem and Wikipedia. Educational reference only.