Mendelevium

Mendelevium is a synthetic chemical element; it has symbol Md (formerly Mv) and atomic number 101. A metallic radioactive transuranium element in the actinide series, it is the first element by atomic number that currently cannot be produced in macroscopic quantities by neutron bombardment of lighter elements. It is the third-to-last actinide and the ninth transuranic element. It can only be produced in particle accelerators by bombarding lighter elements with charged particles. Seventeen isotopes are known; the most stable is ²⁵⁸Md with half-life 51 days; however, the shorter-lived ²⁵⁶Md (half-life 1.17 hours) is most commonly used in chemistry because it can be produced on a larger scale.

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Mendelevium, ₁₀₁Md

Mendelevium
Pronunciation	/ˌmɛndəˈliːviəm/ (MEN-də-LEE-vee-əm) /ˌmɛndəˈleɪviəm/ (MEN-də-LAY-vee-əm)
Mass number	[258]
Mendelevium 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 Tm ↑ Md ↓ (Upp) fermium ← mendelevium → nobelium
Atomic number (Z)	101
Group	f-block groups (no number)
Period	period 7
Block	f-block
Electron configuration	[Rn] 5f13 7s2
Electrons per shell	2, 8, 18, 32, 31, 8, 2
Physical properties
Phase at STP	solid (predicted)
Melting point	1100 K ​(800 °C, ​1500 °F) (predicted)
Density (near r.t.)	10.3(7) g/cm3 (predicted)[1][lower-alpha 1]
Atomic properties
Oxidation states	+2, +3
Electronegativity	Pauling scale: 1.3
Ionization energies	1st: 636 kJ/mol [2]
Other properties
Natural occurrence	synthetic
Crystal structure	​face-centered cubic (fcc) (predicted)[1]
CAS Number	7440-11-1
History
Naming	after Dmitri Mendeleev
Discovery	Lawrence Berkeley National Laboratory (1955)
Isotopes of mendelevium v e
Main isotopes[3] Decay abun­dance half-life (t1/2) mode pro­duct 256Md synth 1.17 h ε 256Fm 257Md synth 5.52 h ε 257Fm α 253Es SF – 258Md synth 51.5 d α 254Es ε 258Fm β− 258No 259Md synth 1.60 h SF – α 255Es 260Md synth 31.8 d SF – α 256Es ε 260Fm β− 260No
Category: Mendelevium view talk edit | references

Mendelevium was discovered by bombarding einsteinium with alpha particles in 1955, the method still used to produce it today. It was named after Dmitri Mendeleev, father of the periodic table of the chemical elements. Using available microgram quantities of einsteinium-253, over a million mendelevium atoms may be made each hour. The chemistry of mendelevium is typical for the late actinides, with a preponderance of the +3 oxidation state but also an accessible +2 oxidation state. All known isotopes of mendelevium have short half-lives; there are currently no uses for it outside basic scientific research, and only small amounts are produced.