Actinium (Ac), element 89 – Learn Acer periodic table

Actinide, atomic number 89.

Actinium is a radioactive chemical element with symbol Ac (not to be confused with the abbreviation for an acetyl group) and atomic number 89, which was discovered in 1899. It was the first non-primordial radioactive element to be isolated. Polonium, radium and radon were observed before actinium, but they were not isolated until 1902.

Symbol Ac. Atomic mass 227.0 u. Group 3, period 7. Electron configuration [Rn] 6d1 7s2. Electrons per shell 2, 8, 18, 32, 18, 9, 2. State at room temperature: Solid. Melting point 1226.8 °C, boiling point 3226.8 °C. Discovered by Friedrich Oskar Giesel.

Element data from Wikipedia, CC BY-SA 3.0.

Actinium (Ac), element 89 – Learn Acer periodic table

Actinium

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