Atomic number 99
Einsteinium
Actinide
No photo: here’s why
Einsteinium has only been made in invisible trace amounts; the largest samples ever made glow from their own radioactivity. Essentially no one has seen it.
Quick facts
- Atomic mass
- 252.00
- Group
- –
- Period
- 7
- State (STP)
- solid
- Electronegativity
- 1.30
- Common ox. states
- +3
Properties
[Rn] 5f¹¹ 7s²
- Ionization energy
- 619.0 kJ/mol
- Electron affinity
- –
- Melting point
- 1133.00 K (859.9 °C)
- Boiling point
- 1269.00 K (995.9 °C)
How dangerous is it?
Made only a few atoms to a speck at a time, this metal is so short lived and radioactive it barely exists outside a lab.
- RadioactiveImmediate and cumulative
It decays so fast that even a microscopic amount is fiercely radioactive, glowing and heating from its own alpha output. (exists only as a trace in research, never in any everyday setting)
Studied in trace amounts only, behind heavy shielding and remote handling at a few licensed labs.
How it bonds· family overview
Einsteinium (Es) is an actinide. Like the lanthanides it tends toward a +3 oxidation state, but the early actinides (Th–Am) routinely access +4, +5, +6, even +7 because the 5f electrons are easier to ionize. Most actinides are radioactive; their "bonding" in school is read off the periodic table, not measured in lab.
