Einsteinium (Es)

Silvery; glows blue in the dark

Einsteinium was discovered in the debris of the first hydrogen bomb explosion in 1952, and with [Rn] 5f¹¹ 7s², einsteinium-252 (half-life 471.7 days) was produced in megaton quantities during thermonuclear tests. The total amount ever produced is less than 1 milligram, making it one of the rarest synthetic elements.

Key metrics

Density8.8g/cm³

Melting point1,133K

Boiling point1,269K

Electronegativity1.3Pauling

Discovery

1952discovered

Discovered by: Lawrence Berkeley Lab
Reactivity profile: Highly radioactive synthetic element
Reactivity: High
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Rn]}\; \textcolor{#a855f7}{5_{f}^{11}}\; \textcolor{#ef4444}{7_{s}^{2}}

[Rn] 5f11 7s2

Wave function

\Psi_{\text{Es}} \approx \frac{1}{\sqrt{99!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{99}(\mathbf{r}_{99}) \right|

Probability density $|\Psi|^2$ across the Es valence shell.

Crystal structure

Face-Centered Cubic

Lattice constantsa = 1.00

Cell anglesα = β = γ = 90°

Coordination number12

Atoms per cell4

Atomic packing factor0.74

Physical properties

Atomic radius: 186 pm
Ionization energy: 619 kJ/mol
Electron affinity: 0 kJ/mol
Crystal structure: Face-centered cubic

Oxidation states

+2+3

Acid/base

Basic

Strongly acidicStrongly basic

State at 25 °CSolid

1133 K1269 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

430.0nmEs I (blue)Violet60%

485.0nmEs IBlue40%

500.0nmEs I (green)Cyan100%

Dominant line 500.0 nmRange 430–500 nmTransitions 3