On this date in 1955 the element Mendelevium was discovered. Here’s what you might not know.
It’s a synthetic metallic element with the symbol Md and atomic number 101.
That makes it what is called a transuranium element. These are elements with atomic numbers greater than 92, the atomic number of Uranium. All of them are radioactively unstable and decay into other elements. They are all synthetic and none of them occur naturally on Earth, except for neptunium and Plutonium.
It has been predicted that Mendelevium would melt at 1100 K (800 °C, 1500 °F).
It was named after Dmitri Mendeleev, a Russian chemist known for formulating the periodic law and creating a version of the Periodic Table of elements.
It was first synthesised by Albert Ghiorso, Glenn T. Seaborg, Gregory Robert Choppin, Bernard G. Harvey, and team leader Stanley G. Thompson in early 1955 at the University of California, Berkeley, by bombarding another synthetic element called einsteinium with alpha particles.
It was the first element to be synthesized and discovered a few atoms at a time. In about a dozen repetitions of the experiment, the team of scientists produced 17 atoms of mendelevium.
In the periodic table, mendelevium is located to the right of the actinide fermium, to the left of the actinide nobelium, and below the lanthanide thulium.
Seventeen isotopes of mendelevium are known, with mass numbers from 244 to 260.
Mendelevium is the last element with any known isotope that has a half-life longer than a day.
The most stable of its isotopes is mendelevium-258 which has a half life of 51.5 days.
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