99Es252.000
Actinidef-blockRadioactive
Einsteinium
Element 99 on the periodic table, symbol Es, group 3, period 7.
Einsteinium is a synthetic element with symbol Es and atomic number 99. It is the seventh transuranic element, and an actinide. Einsteinium was discovered as a component of the debris of the first hydrogen bomb explosion in 1952, and named after Albert Einstein.
Appearance: silver-colored
Properties
- Atomic Number
- 99
- Atomic Mass
- 252.0000 u
- Group
- 3
- Period
- 7
- Block
- f-block
- Category
- Actinide
- State at 25 °C
- Solid
- Melting Point
- 1,133 K · 859.9 °C
- Boiling Point
- 1,269 K · 995.9 °C
- Density
- 8.84 g/cm³
- Atomic Radius
- Not measured
- Electronegativity
- 1.3
- Oxidation States
- +3
- Abundance in Crust
- Vanishingly rare
- Discovered
- 1952
- Discovered By
- Lawrence Berkeley National Laboratory
Electron Configuration
[Rn] 5f11 7s2
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f11
Ionisation Energies (kJ/mol)
- 1. 619
Elements near Einsteinium
Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.