O mendelevium, symbol Md and atomic number 101, is a chemical element belonging to the actinide group. It has 17 known isotopes, the most half life with 51 days. In solution and in compounds, Md has oxidation numbers +3 and +2. Due to the short half-life, element 101 is not found in nature, requiring its production in the laboratory through nuclear fusion reactions.
The mendelevium was Discovered in 1955, by scientists led by Albert Ghiorso and Glenn Seaborg, from the laboratories of the University of California, Berkeley, in the United States. Its initial synthesis occurred through the bombardment of alpha particles in einsteinium nuclei.
Read too: Seaborgium — data for the element named after scientist Glenn Seaborg
Summary about the mendelevium
It is a chemical element belonging to actinides.
It has 17 known isotopes, the 260Md the most stable.
In solution or in compounds, it presents oxidation number equal to +2 or +3.
It cannot be found in nature, being produced in the laboratory through reactions of Nuclear fusion.
Its discovery took place in 1955, in Berkeley, through the fusion of einsteinium atoms with accelerated alpha particles.
Mendelevium properties
Symbol: md
atomic number: 101
atomic mass: 258 a.m.u.a.
Fusion point: 827°C
electronic configuration: [Rn] 7s2 5f13
most stable isotope: 258MD (51 days)
chemical series: actinides
Mendelevium characteristics
Mendelevium, symbol Md, is a actinide with atomic number 101. There are 17 isotopes of mendelevium, whose masses range from 245 to 260, all of which are not found in the nature, due to its small half-life (time required for the quantity of the species to fall through the half). Thus, mendelevium is a synthetic element, and it is necessary that it be lab-produced.
Despite this, the isotope 258Md has a considerable half-life for elements in this zone of the Periodic table, with 51.5 days. Even so, it is the isotope 256Md, 1.27 hour half-life, the most used for studies about this element.
Although metallic Md has never been produced, it has already been predicted that it would present a divalent metallic state, just like europium (Eu) and ytterbium (Yb).
In solution, it was proved that mendelevium favorably presents the +3 charge, with a chemical behavior similar to the other actinides and lanthanides. But the MD3+ can be easily reduced to Md2+, another common oxidation state.
Read too: Rutherfordium — synthetic element with atomic number 104
Obtaining mendelevium
The preparation of mendelevium in the laboratory, more specifically the 256Md (isotope of this most commonly prepared element), occurs by bombardment of einsteinium isotopes (254And I'm 253Es) by helium ions (He) or by alpha (α) particle bombardment.
\({_2^4}\alpha+{_99^{254}}Es\rightarrow{_101^{256}}Md+2{_0^1}n\)
More than a million isotopes of 256Md can be obtained every hour by this method. the mendelevium is obtained in a metallic foil (as beryllium, aluminum, platinum It is gold) and can be separated from the other by-products of the process by dissolving the metallic foil, followed by coprecipitation with lanthanum fluoride. Afterwards, the Md can be separated on ion exchange resins.
history of mendelevium
Mendelevium is more one of several elements discovered by the laboratories of the University of California, in the city of Berkeley, whose scientific group was led by Albert Ghiorso and Glenn Seaborg.
![Monument to the creator of the Periodic Table, Dmitri Mendeleev, in Saint Petersburg, Russia. [1]](/f/607cee5c1577375c9d8b1196fdf8e353.jpg)
In 1955, the Ghiorso and Seaborg's group bombarded alpha particles into a nucleus of 253es, an atomic target that took more than a year to be synthesized in appreciable quantities for the experiment. Berkeley scientists developed a technique in which the element synthesized in the process was not under the target, but was taken to another collecting material, thus allowing the reuse of the target of s.
In a few hours, a few atoms of 256101 were produced (17 exactly), which began to decay briefly as the half-life is about 78 minutes. O element 101 was named mendelevium in honor of the creator of the Periodic Table, Russian Dmitri Mendeleev.
By Stefano Araujo Novais
Chemistry teacher
