Mendelevium
actinide · period 7 · group 3 · f-block
Mendelevium is a synthetic element with the symbol Md (formerly Mv) and atomic number 101. A metallic radioactive transuranium element in the actinide series, it is the first element by atomic number that currently cannot be produced in macroscopic quantities through neutron bombardment of lighter elements.
What the numbers say
At standard temperature and pressure Mendelevium is a solid, sitting in period 7, group 3 of the f-block.
Its melting point of 1100 K (827 °C) is the 58th highest of the 110 elements with a measured value — mid-range among the elements.
Pauling electronegativity is 1.3. Paired with oxygen (3.44) that is a difference of 2.14, which puts the bond predominantly ionic — expect a stable oxide ceramic.
It is reported in 2 oxidation states (2, 3), which sets how many distinct compounds and phases it can form.
First identified in 1955.
Check it against computed structures
The structure search queries the Materials Project, OQMD and the Open Materials Database for computed crystal structures containing Md — with DFT formation energy, hull stability and band gap where the provider publishes them.
K 2 · L 8 · M 18 · N 32 · O 31 · P 8 · Q 2
Properties
| Atomic number | 101 |
|---|---|
| Atomic mass | 258 u |
| Series | actinide |
| Group | 3 |
| Period | 7 |
| Block | f-block |
| Phase at STP | Solid |
| Melting point | 1100 K (827 °C) |
| Electronegativity (Pauling) | 1.3 |
| Electron configuration | [Rn] 5f¹³ 7s² |
| Oxidation states | 2,3 |
| Discovered | 1955 |
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See Md in context with all 118 elements.
Working with mendelevium in a real design?
Ask the materials chat how Md behaves in your alloy system, what it does to weldability, and which grades to look at — with the source of every number named.