Mendelevium - 101Md: historical information
Mendelevium, the ninth transuranium element of the actinide series to be discovered, was first identified by Seaborg and others in 1955 as a product of the bombardment of the einsteinium isotope 253Es with helium ions. The isotope produced was 256Md, which has a half-life of about 11/4 hours.