Einsteinium

Einsteinium, ₉₉Es

Einsteinium
Pronunciation	/aɪnˈstaɪniəm/ ​(eyen-STY-nee-əm)
Appearance	silvery; glows blue in the dark
Mass number	[252]
Einsteinium in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Ho ↑ Es ↓ (Upt) californium ← einsteinium → fermium
Atomic number (Z)	99
Group	f-block groups (no number)
Period	period 7
Block	f-block
Electron configuration	[Rn] 5f11 7s2
Electrons per shell	2, 8, 18, 32, 29, 8, 2
Physical properties
Phase at STP	solid
Melting point	1133 K ​(860 °C, ​1580 °F)
Boiling point	1269 K ​(996 °C, ​1825 °F) (estimated)
Density (near r.t.)	8.84 g/cm3
Atomic properties
Oxidation states	+2, +3, +4
Electronegativity	Pauling scale: 1.3
Ionization energies	1st: 619 kJ/mol
Spectral lines of einsteinium
Other properties
Natural occurrence	synthetic
Crystal structure	​face-centered cubic (fcc)
Magnetic ordering	paramagnetic
CAS Number	7429-92-7
History
Naming	after Albert Einstein
Discovery	Lawrence Berkeley National Laboratory (1952)
Isotopes of einsteinium v e
Main isotopes Decay abun­dance half-life (t1/2) mode pro­duct 252Es synth 471.7 d α 248Bk ε 252Cf β− 252Fm 253Es synth 20.47 d SF – α 249Bk 254Es synth 275.7 d ε 254Cf β− 254Fm α 250Bk 255Es synth 39.8 d β− 255Fm α 251Bk SF –
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Einsteinium is a synthetic, radioactive transuranic chemical element that has that symbol Es and the atomic number of 99.

Chemistry

Einsteinium is the seventh element in the actinide series. There are 19 different radioactive isotopes, but the most stable one is Es-252, with a half-life of 471.1 days.

It is a soft silvery metal that is somewhat magnetic, though like all actinides, einsteinium is rather reactive. It has many oxides, and bonds with quite a few halogens to make halides.

History

Einsteinium is named after Albert Einstein. It was found for the first time in 1952 by Albert Ghiorso and his team of scientists in the debris of the first hydrogen bomb explosion, and identified as an element at the University of California, Berkeley.

Uses

Einsteinium has been used to create the element Mendelevium for the first time in 1955, although no practical uses are known. It has been used before as a calibration marker in a chemical analysis spectrometer.

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1. ↑ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.