Atomic number 101
Mendelevium
Actinide
No photo: here’s why
Mendelevium is a synthetic element made only in vanishingly small, intensely radioactive amounts - its atoms decay so quickly that no piece big enough to see or photograph has ever existed.
Quick facts
- Atomic mass
- 258.00
- Group
- –
- Period
- 7
- State (STP)
- solid
- Electronegativity
- 1.30
- Common ox. states
- +2, +3
Properties
[Rn] 5f¹³ 7s²
- Ionization energy
- 635.0 kJ/mol
- Electron affinity
- –
- Melting point
- 1100.00 K (826.9 °C)
- Boiling point
- –
How dangerous is it?
Known only from a few atoms made at a time, it is so fleeting and radioactive that you would never encounter it in daily life.
- RadioactiveImmediate and cumulative
It is produced one atom at a time and decays away in moments, every atom intensely radioactive while it lasts. (exists only as a fleeting trace in research, never in bulk)
Studied only as a few atoms inside shielded lab equipment by specialist teams.
How it bonds· family overview
Mendelevium (Md) is an actinide. Like the lanthanides it tends toward a +3 oxidation state, but the early actinides (Th–Am) routinely access +4, +5, +6, even +7 because the 5f electrons are easier to ionize. Most actinides are radioactive; their "bonding" in school is read off the periodic table, not measured in lab.
