101MdMendelevium

Mendelevium is a synthetic element with the 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.

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.

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Atomic properties

Atomic mass(258 u)

Atomic shell

Electron configurationRn 5f13 7s2
Ionization energy(1st) (6.58 eV)
(2nd) (12.4 eV)
(3rd) (24.3 eV)
(4th) (40 eV)
(5th) (54.1 eV)
Shell model
Electrons
k-shell:2
l-shell:8
m-shell:18
n-shell:32
o-shell:31
p-shell:8
q-shell:2

Physical properties

Phasesolid

Temperatures

Melting point(1,100 K)

Heat and conductivity

Thermal conductivity(10 W·m-1·K-1)

Magnetism

Magnetism-

Chemical properties

Basicity-
Oxidation state+2 +3

Electronegativity

Pauling scale1.3
Allred-Rochow scale1.2
Nagle scale1.17

Other properties

Natural occurrencesynthetic
Crystal structureFace-centered cubic
Goldschmidt Classificationsynthetic
Superconductorwithout transition tempperature
Radioactivitysignificantly radioactive