Mendelevium

Mendelevium is a synthetic radioactive chemical element with atomic number 101. It is an actinide whose known isotopes are short-lived and produced in nuclear reactions.

Einsteinium-253: Einsteinium-253 is a radioactive isotope of einsteinium with a half-life of about 20 days. Bombarding this isotope with alpha particles produced the first mendelevium atoms.
Albert Ghiorso: Albert Ghiorso was an American nuclear scientist who helped discover numerous transuranium elements. He co-led the team that produced and identified mendelevium.
Actinide: An actinide is an element in the series from actinium through lawrencium, characterized by filling 5f electron states. Mendelevium is the eleventh member of the actinide series.
Chemical element: A chemical element is a substance defined by atoms with a particular number of protons. Mendelevium’s identity rests on its distinct proton number, despite its tiny production quantities.
Actinide concept: The actinide concept places elements from actinium through lawrencium in a series involving 5f electrons. Mendelevium’s discovery added evidence for the predicted continuation of the actinide series.
Alpha particle: An alpha particle is a helium-4 nucleus containing two protons and two neutrons. Alpha-particle bombardment of einsteinium-253 created mendelevium-256.
Glenn T. Seaborg: Glenn T. Seaborg was an American chemist who helped discover several transuranium elements and developed the actinide concept. The discoverers named mendelevium in his honor.
Periodic table: The periodic table arranges chemical elements by atomic number and recurring chemical properties. Its placement puts mendelevium among the 5f-block actinides.
Oxidation state: Oxidation state is a formal measure of an atom’s electron accounting in a compound or ion. Mendelevium experiments have established +2 and +3 oxidation states.
Periodic law: The periodic law states that elemental properties recur periodically when elements are ordered by atomic number. Mendelevium’s properties and position extended the tested sequence of periodic relationships.

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