Actinium: Description, Properties, Electron Configuration, Uses & Facts

Actinium: Description, Properties, Electron Configuration, Uses & Facts

Unveiling Actinium: A Radiant Element in the Periodic Tapestry


In the vast tapestry of the periodic table, Actinium stands as a remarkable and often overlooked element. With its unique properties and intriguing history, Actinium deserves a closer examination to appreciate its role in both the natural world and various scientific applications.

Basic Information:

Symbol: Ac

Latin Name: Actinium

Atomic Number: 89

Atomic Mass: 227.0278 u

Electron Configuration: [Rn] 6d1 7s2

Electron Configuration 

in long form: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 6d1 7s2

Valence Electron: 2


Position in the Periodic Table:

Actinium resides in period 7, group 3 of the periodic table. It is part of the actinide series, a group of elements characterized by the filling of 5f orbitals. This series includes well-known elements like uranium and thorium.

Chemical and Physical Properties:

Physical State: Actinium is a silvery-white, shiny, and highly radioactive metal.

Density: 10.07 g/cm³

Melting Point: 1050 K (777°C or 1431°F)

Boiling Point: 3198 K (2925°C or 5297°F)

Actinium Compounds:

Actinium forms various compounds, primarily in its +3 oxidation state. Some notable examples include Actinium(III) oxide (Ac₂O₃) and Actinium(III) chloride (AcCl₃). These compounds play a role in research and understanding the chemical behavior of Actinium.

Chemical Reactions with Other Elements:

Actinium, being a reactive metal, readily reacts with oxygen and moisture in the air, forming a white oxide coating. It also reacts with acids to produce Actinium salts, releasing hydrogen gas.

Occurrence and Production:

Actinium is not naturally abundant in the Earth's crust. Instead, it is primarily found in trace amounts within uranium and thorium ores. The element can be obtained through various nuclear reactions or by irradiating radium with neutrons.

Uses and Applications:

Due to its radioactive nature, Actinium finds limited direct applications. However, it serves as a neutron source in some scientific research and medical applications. Actinium-225, a decay product of uranium-233, is used in targeted alpha-particle cancer therapies.

Facts About Actinium:

1. Radioactive Nature: Actinium is highly radioactive, with no stable isotopes. Its most stable isotope, Actinium-227, has a half-life of approximately 21.8 years.

2. Discovery: Friedrich Oskar Hahn and Otto Hahn independently discovered Actinium in 1902. Friedrich Giesel later isolated the element in 1902.

3. Named after 'Actinides': The name Actinium is derived from the Greek word 'aktinos,' meaning ray or beam. This reflects its intense radioactivity.

4. Transition Metal Characteristics: Actinium shares similarities with transition metals due to its electron configuration, despite its placement in the actinide series.


Actinium, with its fascinating properties and unique position in the periodic table, serves as a reminder of the diverse elements that make up our world. From its discovery to its applications in cutting-edge medical treatments, Actinium plays a small but impactful role in the broader scientific landscape. As we delve deeper into the mysteries of the elements, Actinium stands as a shining example of the wonders that can be uncovered in the pursuit of knowledge.

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