Actinium was discovered by André-Louis Debierne, a French chemist in 1899.
Name: Actinium Symbol: Ac Atomic number: 89 Atomic weight: 227.03 State: solid Group, period, block: n/a, 7, f Color: silvery-white Classification: actinide Electron configuration: 6d1 7s2
Density: 10 g/cm-3 Melting point: 1323 K,1050 °C,1922 °F Boiling point: 3471 K,3198 °C,5788 °F
Oxidation states: 3 Electronegativity: 1.1 (Pauling scale) Ionization energies: 1st: 499 kJ·mol-1 Covalent radius: 215 pm Van der Waals radius: no data
Actinium has no stable isotopes. There are 31 known isotopes, from 206Ac to 236Ac, and 2 isomers.