Element Actinium
It is a chemical element with the symbol Ac and atomic number 89. Element Actinium was first isolated by French chemist André-Louis Debierne in 1899. Friedrich Oskar Giesel later independently isolated it in 1902 and, unaware that it was already known, gave it the name emanium
A soft, silvery-white radioactive metal, actinium reacts rapidly with oxygen and moisture in air forming a white coating of actinium oxide that prevents further oxidation.
A trivalent radioactive element and the prototypical member of the actinide family.
Owing to its strong radioactivity, actinium glows in the dark with a pale blue light, which originates from the surrounding air ionized by the emitted energetic particles
Names and Identifiers
| Chemical Formula: | Ac |
| CAS: | 7440-34-8 |
| Molecular Weight: | 227.00000 g/mol |
| EC Number : | n/a |
| MDL Number: | n/a |
| Color: | silvery white |
| Other Names: | Attinio |
| PubChem CID: | 23965 |
| IUPAC Name: | Actinium |
| Inchl: | InChI=1S/Ac |
| InChI Key: | QQINRWTZWGJFDB-UHFFFAOYSA-N |
| Canonical SMILES: | [Ac] |
| ICSC Number: | n/a |
Physical & Chemical Properties
| Phase: | Solid |
| Density: | 10 g/cm³ |
| Boiling Point: | 3500±300 K (3200±300 °C |
| Melting Point: | 1500 K (1227 °C, 2240 °F) |
| Molecular Formula: | Ac |
| Flash Point: | n/a |
| Exact Mass: | 227.02800 |
Naturally occurring actinium is composed of two radioactive isotopes; 227 Ac (from the radioactive family of 235 U) and 228 Ac (a granddaughter of 232 Th).
227 Ac decays mainly as a beta emitter with a very small energy, but in 1.38% of cases it emits an alpha particle, so it can readily be identified through alpha spectrometry.
Radiosotope data
| Isotope | Mass/Da | Half-life | Mode of decay | Nuclear spin | Nuclear magnetic moment |
|---|---|---|---|---|---|
| 224Ac | 224.021708 | 2.7 h | β– to 224Th; α to 220Fr; EC to 224Ra | 0 | |
| 225Ac | 225.02322 | 10.0 d | α to 221Fr | 3/2 | |
| 226Ac | 226.026089 | 1.224 d | β– to 226Th; α to 222Fr; EC to 226Ra | 1 | |
| 227Ac | 227.027750 (3) | 21.77 y | β– to 228Th; α to 224Fr | 3/2 | 1.1 |
| 228Ac | 228.031104 | 6.15 h | β– to 229Th | 3 | |
| 229Ac | 229.03293 | 1.04 h | 3/2 |