Einsteinium

1s² 2s²p⁶ 3s²p⁶d¹⁰ 4s²p⁶d¹⁰f¹⁴ 5s²p⁶d¹⁰f¹¹ 6s²p⁶ 7s²

Einsteinium, named for Albert Einstein, was the seventh transuranic element of the actinide series to be discovered. It 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 thermonucleaar explosion (hydrogen bomb test), which took place in the Pacific in November 1952 (Operation Ivy). They discovered the isotope ²⁵³Es (half-life 20.5 days) that was made by the nuclear fusion of 15 neutrons with ²³⁸U (which then went through seven beta decays). These findings were kept secret until 1955 due to the Cold War.

In 1961, a sufficient amount of einsteinium was synthesized to prepare a microscopic amount of ²⁵³Es. This sample weighed about 0.01 mg. A special magnetic-type balance was used in making this determination. ²⁵³Es so produced was used to produce mendelevium (Element 101). About 3 mg of einsteinium has been produced at Oak Ridge National Laboratories by irradiating for several years kilogram quantities of ²³⁹Pu in a reactor to produce ²⁴²Pu. This was then fabricated into pellets of plutonium oxide and aluminum powder, and loaded into target rods for an initial 1-year irradiation at the Savannah River Plant, followed by irradiation in a HFIR (High Flux Isotopic Reactor). After 4 months in the HFIR the targets were removed for chemical separation of the einsteinium from californium. Nineteen isotopes and isomers of einsteinium are now recognized. ²⁵²Es has the longest half-life (276 days). Tracer studies using ²⁵³Es show that einsteinium has chemical properties typical of a heavy trivalent, actinide element.

Today, einsteinium is produced though a lengthy chain of nuclear reactions that involves bombarding each isotope in the chain with neutrons and then allowing the resulting isotope to undergo beta decay. Since only small amounts of einsteinium have ever been produced, it currently has no uses outside of basic scientific research.

19 radioisotopes of einsteinium have been characterized, with the most stable being ²⁵²Es with a half-life of 471.7 days, ²⁵⁴Es with the longest half-life of 275.7 days, ²⁵⁵Es with a half-life of 39.8 days, and ²⁵³Es 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 ^254mEs (t_½ 39.3 hours). The isotopes of einsteinium range in atomic massfrom 240.069 u (²⁴⁰Es) to 258.100 u (²⁵⁸Es).

²⁵²Es decays into berkelium-248 through alpha decay, into californium-252 through electron capture or into fermium-252 through beta decay.

Isotope	Atomic Mass	Half-Life
²⁴⁰Es	240.06892	~1 seconds
²⁴¹Es	241.06854	10 seconds
²⁴²Es	242.06975	13.5 seconds
²⁴³Es	243.06955	21 seconds
²⁴⁴Es	244.07088	37 seconds
²⁴⁵Es	245.07132	1.1 minutes
²⁴⁶Es	246.07290	7.7 minutes
²⁴⁷Es	247.07366	4.55 minutes
²⁴⁸Es	248.07547	27 minutes
²⁴⁹Es	249.07641	102.2 minutes
²⁵⁰Es	250.07861	8.6 hours
^250mEs		2.22 hours
²⁵¹Es	251.079992	33 hours
²⁵²Es	252.08298	471.7 days
²⁵³Es	253.0848247	20.47 days
²⁵⁴Es	254.088022	275.7 days
^254mEs		39.3 hours
²⁵⁵Es	255.090273	39.8 days
²⁵⁶Es	256.09360	25.4 minutes
^256mEs		7.6 hours
²⁵⁷Es	257.09598	7.7 days
²⁵⁸Es	258.09952	~3 minutes

There is currently no evidence of einsteinium evolved in any biological role. Due to its extreme rarity its only use is in scientific research.

Einsteinium Data

Atomic Structure

Atomic Radius: ~860 pm
Atomic Volume:
Covalent Radius:
Cross Section (Thermal Neutron Capture) Barns: 160
Crystal Structure: Cubic face centered
Electron Configuration:

1s² 2s²p⁶ 3s²p⁶d¹⁰ 4s²p⁶d¹⁰f¹⁴ 5s²p⁶d¹⁰f¹¹ 6s²p⁶ 7s²
Electrons per Energy Level: 2, 8, 18, 32, 29, 8, 2
Ionic Radius: 0.925Å
Filling Orbital: 5f¹¹
Number of Electrons (with no charge): 99
Number of Neutrons (most common/stable nuclide): 153
Number of Protons: 99
Oxidation States: 3
Valence Electrons: 5f¹¹ 7s²

Chemical Properties

Electrochemical Equivalent: 4.74 g/amp-hr
Electron Work Function:
Electronegativity: 1.3 (Pauling); 1.2 (Allrod Rochow)
Heat of Fusion: kJ/mol
Incompatibilities:
Ionization Potential
- First: 6.42
Valence Electron Potential (-eV):

Physical Properties

Atomic Mass Average: 252
Boiling Point:
Coefficient of Lineal Thermal Expansion/K^-1: N/A
Conductivity

Electrical:
Thermal: 0.1 W/cm^oK
Description:

Man made radioactive metal, which is not found in nature
Flammablity Class:
Freezing Point: see melting point
Heat of Vaporization: kJ/mol
Melting Point: 1133^oK, 860°C, 1580°F
Physical State (at 20°C & 1atm): Solid
Specific Heat:

Regulatory / Health

CAS Number
- 7429-92-7
NFPA 704
- Health:
- Fire:
- Reactivity:
- Special Hazard: Radioactive<
- OSHA Permissible Exposure Limit (PEL)
  - No limits set by OSHA
- OSHA PEL Vacated 1989
  - No limits set by OSHA
- NIOSH Recommended Exposure Limit (REL)
  - No limits set by NIOSH
- Levels In Humans:
  Note: this data represents naturally occuring levels of elements in the typical human, it DOES NOT represent recommended daily allowances.
  - Blood/mg dm^-3: N/A
  - Bone: N/A
  - Liver: N/A
  - Muscle: N/A
  - Daily Dietary Intake: N/A
  - Total Mass In Avg. 70kg human: N/A
Who / Where / When / How
- Discoverer: G.R. Choppin, S.G. Thompson, A. Ghiorso and G.G. Harvey
- Discovery Location: Berkeley California United States
- Discovery Year: 1952
- Name Origin:
  
  After the scientist Albert Einstein.
- Abundance:
  - Earth's Crust:
  - Seawater:
  - Atmosphere:
  - Sun (Relative to H=1E¹²): N/A
- Sources:
  
  Made by bombarding uranium with neutrons. World production is probably less than 1 gram per year.
- Uses:
  
  None
- Additional Notes:
  
  In 1952 Einsteinium was discovered in the debris of a thermonuclear explosion test in the Pacific.