Isotopes of mendelevium


is a synthetic element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 256Md in 1955. There are 17 known radioisotopes, ranging in atomic mass from 244Md to 260Md, and 5 isomers. The longest-lived isotope is 258Md with a half-life of 51.3 days, and the longest-lived isomer is 258mMd with a half-life of 57 minutes.

List of isotopes

Chronology of isotope discovery

IsotopeDiscoveredReaction
244Md2020209Bi
245Md1996209Bi
246Md1996209Bi
247Md1981209Bi
248Md1973241Am
249Md1973241Am
250Md1973243Am, 243Am
251Md1973243Am, 243Am
252Md1973243Am
253Md1992243Am
254Md1970253Es
255Md1958253Es
256Md1955253Es
257Md1964252Cf
258Md1970255Es
259Md1982248Cm
260Md1989254Es+18O, 22Ne — transfer