Mendelevium
Mendelevium is a synthetic, intensely radioactive metal notable for how it was discovered: it was the first element ever identified from just a handful of individual atoms, rather than a visible or weighable sample. It has no practical use and is studied purely for what it reveals about the far edge of the periodic table.
- Group · Period
- — · 7
- At room temp
- solid
- Melts at
- 1100 K
- Density
- Not yet available
- Discovered
- 1955
Uses
Mendelevium has no practical use outside of research. It has never been produced in a quantity larger than a small number of atoms at a time, which rules out any industrial or commercial application. Its importance lies in what its discovery demonstrated: that new elements could be confirmed and studied through their radioactive decay alone, even when there were far too few atoms to see, weigh, or handle directly.
History
Mendelevium was first produced in 1955 by a Berkeley team including Albert Ghiorso, Bernard Harvey, Gregory Choppin, Stanley Thompson, and Glenn Seaborg, who bombarded a target of einsteinium — already an exceptionally rare material — with helium ions in a cyclotron. Only a small number of atoms were produced, identified one at a time using a newly developed recoil and detection technique. It was named after Dmitri Mendeleev in recognition of the periodic table he devised, which had anticipated that elements like this one should exist.
Fun facts
- Mendelevium was the first element ever identified from just a handful of individual atoms, rather than any visible quantity of material.
- It's named after Dmitri Mendeleev, who built the periodic table that predicted elements like this one decades before they could actually be made.
- It was created by bombarding einsteinium — itself one of the rarest materials on Earth — with a beam of helium nuclei.
Frequently asked questions
Does mendelevium have any practical use?
No. It has no industrial or commercial application. Its value has been almost entirely scientific, as an early proof that elements could be identified and studied one atom at a time.
How do you study an element when you only have a few atoms of it?
Berkeley researchers pioneered a fast recoil technique: newly formed atoms were knocked out of the target material by the force of the nuclear reaction that made them, captured, and then tracked through their radioactive decay, letting scientists confirm the new element's identity from its decay signature rather than its bulk properties.
Who is mendelevium named after?
Dmitri Mendeleev, the chemist whose 19th-century periodic table left gaps for undiscovered elements and correctly predicted many of their properties — a framework that, generations later, made sense of elements like mendelevium itself.
Isotopes
17 known isotopes
Swipe to see all columns →
| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Md-257 | — | 5.52 h | Electron capture (85%), Alpha decay (15%), Spontaneous fission (1%) | 88,992.47 keV | 7,417.58 keV | 2.30 × 10-20 eV |
| Md-258 | — | 51.50 d | Alpha decay (100%) | 91,690.35 keV | 7,409.66 keV | 1.03 × 10-22 eV |
| Md-260 | — | 31.8 d | Spontaneous fission (42%), Alpha decay (25%), Electron capture (23%) | 96,550 keV | 7,396 keV | 1.66 × 10-22 eV |
Show all 17 isotopes
| Md-244 | — | 0.38 s | Alpha decay (100%), Electron capture / beta-plus decay (14%) | 75,597 keV | 7,438 keV | 1.20 × 10-15 eV |
| Md-245 | — | 0.90 ms | Alpha decay, Spontaneous fission | 75,325 keV | 7,441 keV | 5.07 × 10-13 eV |
| Md-246 | — | 0.9 s | Alpha decay (100%), Spontaneous fission, Electron capture | 76,115 keV | 7,441 keV | 5.07 × 10-16 eV |
| Md-247 | — | 1.2 s | Alpha decay (99.9%), Spontaneous fission (0.1%) | 75,936 keV | 7,444 keV | 3.80 × 10-16 eV |
| Md-248 | — | 7 s | Electron capture (80%), Alpha decay (20%) | 76,948 keV | 7,442 keV | 6.52 × 10-17 eV |
| Md-249 | — | 21.7 s | Alpha decay (60%), Electron capture / beta-plus decay (40%) | 77,180.95 keV | 7,444.02 keV | 2.10 × 10-17 eV |
| Md-250 | — | 52 s | Electron capture (93%), Alpha decay (7%) | 78,399.14 keV | 7,441.65 keV | 8.77 × 10-18 eV |
| Md-251 | — | 4.0 m | Electron capture / beta-plus decay (90%), Alpha decay (10%) | 78,966.75 keV | 7,441.9 keV | 1.90 × 10-18 eV |
| Md-252 | — | 2.3 m | Electron capture (100%) | 80,467.12 keV | 7,438.44 keV | 3.31 × 10-18 eV |
| Md-253 | — | 6 m | Electron capture / beta-plus decay (99.3%), Alpha decay (0.7%) | 81,173 keV | 7,438 keV | 1.27 × 10-18 eV |
| Md-254 | — | 10 m | Electron capture / beta-plus decay (100%) | 83,453 keV | 7,432 keV | 7.60 × 10-19 eV |
| Md-255 | — | 27 m | Electron capture (93%), Alpha decay (7%) | 84,842.07 keV | 7,428.73 keV | 2.82 × 10-19 eV |
| Md-256 | — | 77.7 m | Electron capture (90.8%), Alpha decay (9.2%), Spontaneous fission (3%) | 87,456 keV | 7,421 keV | 9.79 × 10-20 eV |
| Md-259 | — | 1.60 h | Spontaneous fission (100%), Alpha decay (1.3%) | 93,564 keV | 7,405 keV | 7.92 × 10-20 eV |