General:

Name: Mendelevium
Type: Actinide
Density @ 293 K: g/cm3

Discovery of Mendelevium
Mendelevium was the ninth synthetic transuranium element of the actinide series to be discovered.

It was first identified by Albert Ghiorso, Bernard Harvey, Gregory Choppin, Stanley Thompson, and Glenn Seaborg in 1955 at the Lawrence Berkeley National Laboratory, California.

Mendelevium-256 (half-life 78.1 minutes) was produced by bombarding einsteinium-253 with alpha particles in the Berkeley 60-inch cyclotron.

Only 17 atoms of mendelevium-256 were initially produced in an all night experiment predicted to produce just one or two atoms of product every three hours. Each nuclear reaction created mendelevium-256 and a neutron. (1), (2), (3)
Symbol: Md
Atomic weight: 258
Atomic volume: cm3/mol


Mendelevium was identified by chemical analysis in an ion exchange experiment. (1)

The element is named after the chemist Dmitri Mendeleev who devised the first periodic table in modern form.

States

State (s, l, g): solid
Melting point: 1100 K   (827 oC)

Boiling point: K   ( oC)

Energies

Specific heat capacity: J g-1 K-1
Heat of fusion: kJ mol-1
1st ionization energy: 635 kJ mol-1
3rd ionization energy: kJ mol-1
Heat of atomization: kJ mol-1
Heat of vaporization: kJ mol-1
2nd ionization energy: kJ mol-1
Electron affinity: kJ mol-1

Oxidation & Electrons

Shells: 2,8,18,32,31,8,2
Minimum oxidation number: 0
Min. common oxidation no.: 0
Electronegativity (Pauling Scale): 1.3
Electron configuration: [Rn] 5f12 7s2
Maximum oxidation number: 3
Max. common oxidation no.: 3
Polarizability volume: 18.2 Å3

Appearance & Characteristics

Structure: close packed cubic
Hardness: mohs

Berkeley 60-inch cyclotron
Many transuranium elements including mendelevium were discovered with the 60-inch cyclotron (shown above) at the University of California Lawrence Radiation Laboratory, Berkeley.
Color:


Harmful effects:
Mendelevium is harmful due to its radioactivity.

Characteristics:
Mendelevium is a synthetic, highly radioactive metal and has only been produced in miniscule amounts. Mendelevium was the first element to be produced one atom at a time.

Mendelevium metal has not been prepared. (3a)

Uses:
Mendelevium is of scientific research interest only.

Reactions & Compounds

Reaction with air:
Reaction with 15 M HNO3:
Oxide(s):
Hydride(s):
Reaction with 6 M HCl:
Reaction with 6 M NaOH:
Chloride(s):

Radius

Atomic radius: pm
Ionic radius (2+ ion): pm
Ionic radius (2- ion): pm
Ionic radius (1+ ion): pm
Ionic radius (3+ ion): 89.6 pm
Ionic radius (1- ion): pm

Conductivity

Thermal conductivity: W m-1 K-1
Electrical conductivity: x 106 S cm-1

Abundance & Isotopes

Abundance earth's crust: nil
Abundance solar system:
Cost, pure: $ per g
Cost, bulk: per 100g

Source: Mendelevium is a synthetic element and is not found naturally. Mendelevium is produced through charged-particle of lighter elements in particle accelerators.

Isotopes: Mendelevium has 16 isotopes whose half-lives are known, with mass numbers 245 to 260. Mendelevium has no naturally occuring isotopes. Its longest lived isotopes are 258Md with a half-life of 51.5 days, 260Md, with a half-life of 31.8 days and 259Md with a half-life of 96 minutes.


References

1. Glenn 1. Seaborg, The Transcalifornium Elements., Journal of Chemical Education, Vol 36.1 (1959) p39.
2. John Emsley, Nature's building blocks: an A-Z guide to the elements., Oxford University Press, 2003., p458.
3. Robert J. Silva, The Chemistry of the Actinide and Transactinide Elements., Springer., Vol 3.13, p1630 - 1631.
3a. Robert J. Silva, The Chemistry of the Actinide and Transactinide Elements., Springer., Vol 3.13, p1634.

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