#89 Actinium

Actinium is a chemical element with symbol Ac and atomic number 89. It was discovered by Friedrich Oskar Giesel in 1902, who isolated the element the same year. Actinium gave the name to the actinide series, a group of 15 similar elements between actinium and lawrencium in the periodic table.

Atomic mass:(227.0) amu

Melting point:1050.0 C (1323.15 K, 1922.0 F)

Boiling point:3200.0 C (3473.15 K, 5792.0 F)

Density:293 K: 10.07 g/cm3