Actinium (Ac)

About Actinium

Actinium is a chemical element with the symbol Ac and atomic number 89, meaning every atom has 89 protons in its nucleus. It is classed as Actinide and is a solid at room temperature. Its atomic mass is about 227 atomic mass units (u).

On the periodic table, Actinium sits in group 3, period 7 (actinide series), which determines how many electron shells it has and how it tends to react with other elements.

Uses of Actinium

In daily life and industry, Actinium is used for Radioactive. These uses are closely tied to the typical properties of elements in the Actinide category.

Electron Structure of Actinium

Using a simplified electron shell model (at most 2 electrons in the first shell, 8 in the second, 18 in the third, and so on), Actinium has 5 electron shells, with an approximate arrangement of 2, 8, 18, 32, 29 electrons from the innermost shell to the outermost. This is a simplified learning model, not the full electron configuration that accounts for the s, p, d and f subshells.

Explore Other Elements

Want to see another element or try the element symbol quiz? Go back to the Interactive Periodic Table to explore all 118 chemical elements.

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