89Ac
Actinium
ActinideActinium (Ac) is element 89, an actinide, in period 7 and group 3 of the periodic table. Its atomic mass is usually given as 227, it melts at 1050 °C and boils at 3200 °C. Discovered by Friedrich Oskar Giesel, 1902.
Atomic Number89
SymbolAc
NameActinium
Atomic Weight227 u
CategoryActinide
Period7
Group3
Melting Point1050 °C
Boiling Point3200 °C
Density10.07 g/cm³
Electron Config[Rn] 6d1 7s2
Discovered ByFriedrich Oskar Giesel, 1902