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californium – einsteinium – fermium
Er Es
	Full table

Known properties

Name, Symbol, Number

Einsteinium, Es, 99

Chemical series

Actinides

Period, Block

7 , f

Appearance

unknown; probably metallic,
silvery white or gray

Atomic weight

1 E-25 kg|[252] amu]]

Electron configurationElectron configuration is the arrangement of electrons in an atom, molecule or other body. Specifically, it is the placement of electrons into atomic, molecular, or other forms of electron orbitals. Orbitals, states, and wavefunctions Since electrons are

probably [ RnAstatine Radon Xe Rn Uuo Full table General Name, Symbol, NumberRadon, Rn, 86 Chemical series Noble gases Group, Period, Block 18 (VIIIA), 6 , p Density, Hardness 9. 73 kg/m3 (273 K), NA Appearance colorless Atomic properties Atomic weight [222] amu Atomi]5f¹¹ 7 s²

e^-The electron (also called negatron commonly represented as e&minus is a subatomic particle. In an atom the electrons surround the nucleus of protons and neutrons in an electron configuration. Electrons have the smallest electrical charge and when they mov 's per energy levelAn energy level is a quantified stable energy, which a physical system can have; the term is most commonly used in reference to the electron configuration of electrons, in atoms or molecules. According to quantum theory, only certain energy levels are pos

2, 8, 18, 32, 29, 8, 2

State of matter

SolidA solid is a state of matter, characterized by a definite volume and a definite shape (i. it resists deformation). Within a solid, atoms/ molecules are relatively close together, or "rigid"; however, this does not prevent the solid from becoming deformed

Most stable isotopes

isoIsotopes are atoms of a chemical element whose nuclei have the same atomic number, Z but different atomic weights, A''. The word isotope meaning at the same place comes from the fact that isotopes are located at the same place on the periodic table. The a	NA	half-life	DM	DE M eV	DP
²⁵²Es	{syn.}	471.7 d	α ε β^-	6.760 1.260 0.480	²⁴⁸ Bk ²⁵² Cf ²⁵² Fm
²⁵³Es	{syn.}	20.47 d	SF α	n/a 6.739	n/a ²⁴⁹Bk
²⁵⁴Es	{syn.}	275.7 d	ε β^- α	0.654 1.090 6.628	²⁵⁴Cf ²⁵⁴Fm ²⁵⁰Bk
²⁵⁵Es	{syn.}	39.8 d	β^- α SF	0.288 6.436 n/a	²⁵⁵Fm ²⁵¹Bk n/a

Einsteinium is a synthetic element in the periodic table that has the symbol Es and atomic number 99. A metallic highly radioactive transuranic element (7th in the series) in the actinides, einsteinium is produced by bombarding plutonium with neutrons and was discovered in the debris of the first hydrogen bomb test. It was named after Albert Einstein and has no known uses. Tracer studies using the isotope Es-253 show that einsteinium has chemical properties typical of a heavy trivalent, actinide element.

1 History

Einsteinium was first identified in December 1952 by Albert Ghiorso at the University of California, Berkeley and another team headed by G.R. Choppin at Los Alamos National Laboratory. Both were examining debris from the first hydrogen bomb test of November, 1952 (see Operation Ivy). They discovered the isotope einsteinium-253 ( half-life 20.5 days) that was made by the nuclear fusion of 15 neutrons with uranium-238 (which then went through seven beta decays). These findings were kept secret until 1955 due to Cold War tensions, however.

In 1961, enough einsteinium was synthesized to prepare a macroscopic amount of Es-253. This sample weighed about 0.01 mg and was measured using a special balance. The material produced was used to produce mendelevium. Further einsteinium has been produced at the Oak Ridge National Laboratory's High Flux Isotope Reactor in Tennessee by bombarding plutonium-239 with neutrons. Around 3 mg was created over a four year program of irradiation and then chemical separation from a starting 1 kg of plutonium isotope.

2 Isotopes

17 radioisotopes of einsteinium have been characterized, with the most stable being Es-252 with a half-life of 471.7 day, Es-254 with a half-life of 275.7 day, Es-255 with a half-life of 39.8 days, and Es-253 with a half-life of 20.47 days. All of the remaining radioactive isotopes have half-lifes that are less than 40 hours, and the majority of these have half lifes that are less than 30 minutes. This element also has 3 meta states, with the most stable being Es-254m (t_½ 39.3 hours). The isotopes of einsteinium range in atomic weight from 240.069 amu (Es-240) to 257.096 amu (Es-257).

3 References

Los Alamos National Laboratory - Einsteinium
Guide to the Elements - Revised Edition, Albert Stwertka, (Oxford University Press; 1998) BooksEnthsiast.com
It's Elemental - Einsteinium

4 External links

WebElements.com - Einsteinium (also used as a reference)
EnvironmentalChemistry.com - Einsteinium (also used as a reference)

Chemical elements Actinides

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