99 Es 252
Einsteinium
Actinide
Einsteinium (Es) is a chemical element with atomic number 99, classified as a actinide. At room temperature it is a solid. It was discovered in 1952 by Albert Ghiorso et al..
Properties
- Atomic number
- 99
- Atomic mass
- 252 u
- Category
- Actinide
- Group
- 0
- Period
- 7
- Block
- f-block
- Electron configuration
- [Rn] 5f¹¹ 7s²
- Phase at STP
- Solid
- Density
- 8.84 g/cm³
- Melting point
- 1133 K (859.9 °C)
- Boiling point
- 1269 K (995.9 °C)
- Electronegativity
- 1.3
- Atomic radius
- 245 pm
- Ionization energy
- 6.42 eV
- Discovery
- 1952 · Albert Ghiorso et al.
Common uses
Research only
Did you know?
Named after Albert Einstein and first found in hydrogen bomb debris.
Experiment with the elements
Einsteinium doesn't form any compounds in our lab yet, but the periodic table sandbox lets you combine dozens of other real elements into real compounds — water, table salt, ammonia and many more — with their true chemical formulas.