Mendelevium

Mendelevium, chemical element, symbol Md; for physical constants see Periodic Table. An artificial radioactive element, mendelevium was discovered by Albert Ghiorso and his co-workers in 1955. Einsteinium-253 was bombarded with helium ions in the 60-inch cyclotron in Berkeley. Mendelevium-256, having a half-life of 76 minutes, was produced. That is the longest-lived isotope of the element known. It is a metallic element and a member of the actinide series. Fourteen radioactive isotopes of mendelevium have been produced.