Atomic Element Z = 99 • Actinide
Einsteinium (Es) — Atomic Data, Electron Shells & Reactions
Einsteinium (symbol Es, atomic number 99) has a standard atomic weight of 252 u and ground-state configuration [Rn] 5f11 7s2.
Atomic Number (Z)
99
IUPAC Symbol
Es
Standard Atomic Weight
252 g/mol
Period / Group / Block
7 / f-block / f-block
Condensed Electron Config
[Rn] 5f11 7s2
Full Subshell Config
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 5f11 6s2 6p6 7s2
Principal Shell Occupancy
[2, 8, 18, 32, 29, 8, 2]
Pauling Electronegativity
1.3
First Ionization Energy
619 kJ/mol
Covalent Radius
165 pm
Melting Point
1133 K (859.85 °C)
Boiling Point
1269 K (995.85 °C)
Density
8.84 g/cm³
Oxidation States
+3
Es (Z=99) — Valence shell highlighted in vermilion