A radioactive metal, of which only a few atoms have ever been created.
| Density | Unknown |
| Melting Point | 827°C |
| Boiling Point | Unknown |
Mendelevium is used only for research.
Seventeen atoms of mendelevium were made in 1955 by Albert Ghiorso, Bernard Harvey, Gregory Chopin, Stanley Thompson, and Glenn Seaborg. They were produced during an all-night experiment using the cyclotron at Berkeley, California. In this, a sample of einsteinium-253 was bombarded with alpha-particles (helium nuclei) and mendelevium-256 was detected. This had a half-life of around 78 minutes. Further experiments yielded several thousand atoms of mendelevium, and today it is possible to produce millions of them. The longest lived isotope is mendelevium-260 which has a half-life of 28 days.