Actinium
Definition and meaning of Actinium in chemistry.
Actinium is a soft, silvery white radioactive metal with the symbol Ac and atomic number 89. It is the first element of the actinide series, lending its name to this entire group of elements. The metal is highly radioactive and glows with a pale blue light in the dark due to the emission of energetic particles.
In more detail
Located in period 7 of the periodic table, actinium shares remarkably similar chemical properties with lanthanum, serving as its heavier analog and the namesake of the entire actinide series. It occurs naturally in incredibly minuscule quantities within uranium ores, arising solely as a transient decay product of the uranium-235 isotope. The element lacks any stable isotopes, with actinium-227 representing the most long lived naturally occurring isotope with a relatively brief half-life of 21.77 years. Because of its extreme natural scarcity, the vast majority of actinium utilized for scientific research is produced artificially by irradiating radium-226 with neutrons inside a nuclear reactor. Its intense radioactivity makes it exceedingly dangerous to manipulate, and the pure metal rapidly oxidizes in atmospheric oxygen to form a highly resilient protective coating of actinium oxide. Actinium chemistry is almost entirely dominated by the +3 oxidation state, forming colorless compounds that exhibit strong basicity in aqueous solutions.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Ac |
| Atomic number | 89 |
| Atomic mass | [227] u |
| Category | Actinide |
| State at room temperature | Solid |
| Melting point | 1050 degrees Celsius |
| Common oxidation state | +3 |
Actinium-225 is actively researched for use in targeted alpha therapy to treat various forms of cancer by delivering lethal radiation directly to tumor cells.
Frequently asked questions
How is actinium obtained for scientific research?
While trace amounts exist in uranium ores, it is typically synthesized in nuclear reactors through the deliberate neutron bombardment of radium.
Why is actinium being used in cancer research?
Certain isotopes of actinium emit highly energetic alpha particles which can destroy cancer cells with high precision while minimizing damage to surrounding healthy tissue.