Mendelevium - Md
Mendelevium (Md)
Mendelevium is a radioactive actinide produced in very small quantities. It does not have a standard atomic weight; the bracketed value below identifies a representative isotope mass number.
| Atomic number | 101 |
|---|---|
| Representative isotope mass number | [258] |
| Electron configuration | [Rn] 5f13 7s2 |
| Density | not established |
| Melting point | 827 (estimated) °C |
| Boiling point | not established |

Uses and applications
Mendelevium is produced atom by atom and is used only for research. Its short-lived isotopes allow scientists to investigate the chemistry of elements near the end of the actinide series.
Mendelevium and water management
Mendelevium is not used in water treatment and is not expected in ordinary water supplies. Any occurrence in research or nuclear waste requires radionuclide-specific controls.
Occurrence and environmental context
Mendelevium is a synthetic actinide with no stable isotopes. Its occurrence outside controlled production is extremely limited. Environmental assessment, if relevant, depends on isotope, activity, chemical form, and the specific source.
Health and safety
Mendelevium requires specialised radiological controls. Exposure risk depends on isotope, activity, chemical form, and exposure route. Follow applicable radiation-protection procedures and institutional requirements when handling radioactive materials or waste.
Back to the periodic table of elements
Sources and further reading
Element page last reviewed: 24 October 2026 by Lenntech.