99 - Einsteinium actinide
Discovered by Lawrence Berkeley Laboratory in 1952
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.
Periodic table
| Shell | Electrons | Orbitals |
|---|---|---|
| 1 | 2 | 2 in 1s |
| 2 | 8 | 2 in 2s + 6 in 2p |
| 3 | 18 | 2 in 3s + 6 in 3p + 10 in 3d |
| 4 | 32 | 2 in 4s + 6 in 4p + 10 in 4d + 14 in 4f |
| 5 | 29 | 2 in 5s + 6 in 5p + 10 in 5d + 11 in 5f |
| 6 | 8 | 2 in 6s + 6 in 6p |
| 7 | 2 | 2 in 7s |
Electron shells
silver-colored Appearance
252 u Atomic Mass
13 Group
3 Common Oxidation States
8.84 g/cm³ Density
−28.6 kJ/mol Electron Affinity
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f11 Electron Configuration
[Rn] 5f11 7s2 Electron Configuration (semantic)
1.3 Electronegativity
99 Electrons
6.42 eV First Ionization Energy
619 kJ/mol Ionization Energies
1.13k K Melting Point
38 Mendeleev Number
7 Number of Shells
153 Neutrons
99 Atomic Number
123 Number of Isotopes
2, 3 Oxidation States
7 Period
Solid Phase
99 Protons