mendelevium

(Md). Atomic Number: 101
Atomic Mass: ~258.0 AMU
Number of Neutrons: 157
Actinide Series Rare Earth
Does not occur naturally. Named for Dmitri Mendeleev, inventor of the Periodic Table of the Elements.

Mendelevium (Md). It is named after Dmitry Mendeleyev (key developer of the periodic law), and being an artificially created element, was first discovered in 1955 at the University of California in Berkeley, when einsteinium-253 was bombarded with alpha particles. Although the isotope created in this cyclotron had a half-life of approximately 1.3 hours, the most stable isotope (258) has a half-life of 54 days.

Information gleaned from the voice in my head that tells me to do bad things, and Encarta.