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What is Mendelevium

Mendelevium (pronounced as men-deh-LEE-vee-em) is a radioactive metal that belongs to the family of actinides and represented by the chemical symbol Md. Its most stable isotope is Md-258 with a half-life of 51.5 days [1, 4].


Origin of its Name: The element is named in honor of Dmitri Mendeleev, a Russian chemist who formulated one of the first periodic tables [1].

Who Discovered it: Albert Ghiorso and his team of researchers comprising of Gregory Chopin, Bernard Harvey, Glenn Seaborg, and Stanley Thompson were responsible for its discovery [1].

When and Where was Mendelevium Discovered

In 1955, Ghiorso and his team at Berkeley, California, conducted an all-night experiment where a sample of einsteinium-253 was bombarded with alpha particles in a cyclotron to produce a new isotope, later detected as mendelevium-256 with a half-life of about 78 minutes. After this, several other isotopes of the new metal were synthesized at the laboratory [1].


Mendelevium Identification

Atomic number 101 [1]
CAS number 7440-11-1 [1]
Position in the periodic table [1] Group Period Block
Actinides 7 f

Properties and Characteristics of Mendelevium

General Properties

Relative atomic mass 258 [1]
Atomic mass 258 atomic mass units [5]

Physical Properties

Color/appearance Unknown [1]
Melting point/freezing point 827°C (1521°F) [1]
Boiling point Unknown [1]
Density Unknown [1]
State at standard room temperature (solid/liquid/gas) Solid [1]
Electrical conductivity Unknown [1]

Chemical Properties

Oxidation states 3 [1]

Atomic Data of Mendelevium (Element 101)

Valence electrons 3 [6]
Electron configuration (noble gas configuration) [Rn] 5f137s2 [1]
Atomic structure [3]
–          Number of Electrons 101
–          Number of Neutrons 157
–          Number of Protons 101
Radius of atom
       –       Atomic Radius 2.46 Å [1]
       –       Covalent Radius 1.73 Å [1]
Ionization energy [1]


1st 2nd 3rd 4th 5th 6th 7th

Mendelevium Atomic Structure (Bohr Model)

What is Mendelevium Used for

The short half-life of Md makes it difficult to study its properties in detail, and determine any uses. As a result, it is artificially synthesized whenever required for scientific studies [1].

Interesting Facts

  • As naming the element after a Russian chemist was a bold decision taken in the middle of the Cold War, Glenn Seaborg had to take permission from the U.S government before officially declaring the discovery of mendelevium [7].
  • The proposed symbol for the element was Mv, but IUPAC changed it to Md in 1957, at their assembly in Paris [7].

Mendelevium Cost

Since the element is artificially prepared in the laboratory, it cannot be commercially availed.



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