Mendelevium and a crater, memorials to Mendeleev

Mendelevium is an unstable element, number 101 on the periodic table. It is named after the Russian scientist Dmitri Mendeleev who is credited with the formulation of the periodic table of elements.

February 8 is not just Mardi Gras, it is Mendeleev’s 182nd birthday. The periodic table of Mendeleev was published in its first version in 1869. The memorial to Dmitri Mendeleev, element 101, sits snugly between the memorial to Fermi (Fermium) at element 100 and that to Nobel (Nobelium) at 102.

Directly above Mendelevium in the Mendeleev periodic table is Thulium, element 69, named after the ancient Greek site of Thule as remembered in Scandinavian texts. The difference in atomic number between Thulium (Tm) in the lanthanide series and Mendelevium in the actinide series is 32 representing, in classical electron structure, 2 s shell electrons, 6 p shell electrons, 10 d shell electrons, and 14 f shell electrons. Exciting as this is, it was effectively forecast by Mendeleev that Thulium, which was not known till 1879, should exist, and Dmitri Mendeleev would have had little trouble, brilliant scientist that he was, in predicting not only the chemistry of Thulium but also that of his namesake element.

To the extent that Thulium is a rare element on the earth, Mendelevium is totally scarce except when produced by alpha particles (He) bombardment of einsteinium (named after another reasonably well known scientist).

This technique was developed in 1952 and it was not until 1955, some 48 years after the last breaths of Mendeleev, that scientists at University of California Berkeley synthesized from a target of 1 billion atoms of einsteinium, the magical quantity of 17 atoms of Mendelevium. One isotope of Mendelevium with 157 neutrons (Md 258) has a half life of over 50 days so in the scheme of transuranide elements is moderately stable.

Yet, whereas Mendeleev left a legacy in his periodic table, his element has no use at all except to fill scientific texts. Mendeleev was not the first to attempt to find order within the elements, scientists throughout Europe had been delving into the structuring of the elements since Lavoisier 80 years earlier in 1789.

Mendeleev discovered the Periodic System while trying to arrange the elements in February of 1869, 147 years ago. He wrote the properties of the elements on pieces of card and shuffled them backwards and forwards until it occurred to him that, by putting them in order of increasing atomic weight, certain types of element regularly occurred. His first table had the elements with similar properties in rows, but he modified it to put them in columns (e.g. Be, Mg, Ca, Sr, Ba).

Mendeleev’s wit was to shift elements around even though this may disrupt the series of atomic weights. Elements had to fit into his pattern. The example mostly given is the rearranging of Iodine and tellurium, because iodine chemistry was very similar to fluorine, chlorine and bromine. He predicted Gallium calling it eka-aluminium, Scandium (element 21) and Germanium (obvious now as a semiconducting element) that sits below silicon. These elements were not physically discovered until 1886. It is pertinent that the discovery of the noble gases (helium, neon, argon, krypton, xenon, radon) was the confirming grace for Mendeleev’s ‘system’.

Though he was not awarded a Nobel prize, Mendelevium is not his only memorial. A large whole in the ground on the moon is named after him. ‘Crater Mendeleev’ is on the other side of the moon.

More regard seems to have been shown by his Russian colleagues. In Moskovskiy Prospekt in St Petersburg, next to the building of the Bureau of Weights and Measures, where Mendeleev had worked as director and famously introduced new standards for the production of vodka, sits a large statue of Mendeleev as an old man. The monument is a short walk from St. Petersburg Technological Institute, where Mendeleev gained his first professorship in 1864.

(This article is published under licence from Energitismo Limited)