Nuclides
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Chemical element · Atomic number 99
Einsteinium (Es)
Actinides · Period 7 · Solid
Element identity
- Atomic number (Z)
- 99
- Symbol
- Es
- Atomic weight / isotope mass number
- [252]
- Category
- Actinides
- Physical state (reference)
- Solid
- Period
- 7
- Group (reference)
- 3
- Block
- f
Physical properties
- Appearance
- Silver-colored
- Density
- 8.84 g·cm⁻³
- Melting point
- 1133 K / 860 °C / 1580 °F
- Boiling point
- 1269 K / 996 °C / 1825 °F
- Sublimation point
- Not available
Atomic and material properties
- Electron configuration
- [Rn] 5f¹¹ 7s²
- Electrons per shell
- K2 L8 M18 N32 O29 P8 Q2
- Oxidation states
- 2, 3, 4
- Electronegativity (Pauling)
- 1.3
- Atomic radius
- Not available
- Covalent radius
- Not available
- Molar ionization energies
- 1st: 619 kJ·mol⁻¹ 2nd: 1216 kJ·mol⁻¹ 3rd: 2334 kJ·mol⁻¹ 4th: 3734 kJ·mol⁻¹
- Thermal conductivity
- Not available
- Molar heat capacity
- Not available
- Crystal structure
- Face-centered cubic
- CAS number
- 7429-92-7
Property source: Wikipedia — Einsteinium, adapted from the Nuclides App snapshot. Quoted conditions and qualifiers are retained.
Sources and interpretation
Snapshot exported 24 October 2026 from the element assets used by Nuclides. Properties are a reference compilation, not a new evaluation. Missing values are shown as “Not available”. Density and phase depend on temperature, pressure and allotrope; retained conditions are part of the quoted property.
Atomic weight is dimensionless. Parentheses give uncertainty in the last quoted digits. A single integer in square brackets is an isotope mass number, not a standard atomic weight. The snapshot can differ from current evaluations; consult CIAAW standard atomic weights and the IUPAC periodic table for current values and conventions.
Element properties in the App snapshot are adapted from Wikipedia. Each element page links to its source article; text adaptations are available under CC BY-SA 4.0. No third-party images are included.
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