Atomic Element Z = 89 • Actinide
Actinium (Ac) — Atomic Data, Electron Shells & Reactions
Actinium (symbol Ac, atomic number 89) has a standard atomic weight of 227 u and ground-state configuration [Rn] 6d1 7s2.
Atomic Number (Z)
89
IUPAC Symbol
Ac
Standard Atomic Weight
227 g/mol
Period / Group / Block
7 / f-block / f-block
Condensed Electron Config
[Rn] 6d1 7s2
Full Subshell Config
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 6d1 7s2
Principal Shell Occupancy
[2, 8, 18, 32, 18, 9, 2]
Pauling Electronegativity
1.1
First Ionization Energy
499 kJ/mol
Covalent Radius
215 pm
Melting Point
1323 K (1049.85 °C)
Boiling Point
3471 K (3197.85 °C)
Density
10.07 g/cm³
Oxidation States
+3
Ac (Z=89) — Valence shell highlighted in vermilion