Actinium

Actinium (Ac) is a radioactive chemical element with the atomic number 89 and symbol Ac. It is a member of the Group 3 elements and is considered to be the first element of the actinide series, although this classification is sometimes disputed. Actinium is silvery-white, soft, and rapidly tarnishes in air, forming a white oxide coating that prevents further oxidation. It is radioactive and emits alpha and beta particles.

Properties:

• Atomic Number: 89
• Atomic Mass: 227 u (most stable isotope)
• Electron Configuration: [Rn] 6d¹ 7s²
• State at Room Temperature: Solid
• Melting Point: 1050 °C (1922 °F; 1323 K)
• Boiling Point: 3198 °C (5788 °F; 3471 K) (estimated)
• Density: 10.07 g/cm³ (estimated)
• Radioactivity: Highly radioactive

Occurrence and Production:

Actinium occurs naturally in trace amounts in uranium ores, such as pitchblende, but it is far more practical to produce it by neutron irradiation of radium-226. The most common isotope is Actinium-227, which has a half-life of 21.772 years.

Isotopes:

Actinium has 36 known isotopes, all of which are radioactive. The most stable isotope is Actinium-227. Actinium-225 is also of interest for medical applications.

Uses:

Due to its radioactivity and scarcity, Actinium has limited uses.

• Neutron Source: Actinium-227, when mixed with beryllium, is an efficient neutron source.
• Radiotherapy (Potential): Actinium-225 is being investigated for targeted alpha therapy in cancer treatment. Its short half-life and high energy alpha particle emission make it potentially effective in destroying cancer cells.
• Scientific Research: Used in research to study the properties of the actinide elements.

Discovery:

Actinium was discovered in 1899 by André-Louis Debierne, who isolated it from pitchblende. He named it "actinium" from the Greek word "aktis," meaning ray or beam. Friedrich Oskar Giesel independently discovered actinium in 1902 and called it "emanium." Debierne's name was eventually adopted.

Precautions:

Actinium is highly radioactive and poses a significant health hazard due to its ability to ionize biological tissue. It should be handled with extreme care and appropriate protective measures, including shielding and containment. Ingestion or inhalation should be strictly avoided.