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General Chemistry

Mendelevium

Definition and meaning of Mendelevium in chemistry.
Mendelevium is a highly radioactive, human-made metal with the chemical symbol Md and atomic number 101. It belongs to the actinide series, which is a group of heavy radioactive elements. Scientists named this element after Dmitri Mendeleev to honor his creation of the periodic table.
Mendelevium element card: symbol Md, atomic number 101, atomic mass [258], electron configuration [Rn] 5f¹³ 7s², oxidation states +3, Actinide, f-block, period 7, solid at room temperature.

In more detail

Mendelevium is a completely artificial element that you will never find in nature. Scientists must carefully create it inside giant machines called particle accelerators. They make it by shooting high-energy alpha particles at lighter radioactive elements like einsteinium.

In water-based solutions, mendelevium mostly shows a +3 oxidation state. This chemical behavior is very common and expected for elements in the actinide series. However, researchers have also seen mendelevium form a +2 oxidation state many times.

This +2 state is surprisingly stable compared to the lighter actinide elements. The physical properties of solid mendelevium metal remain mostly a mystery to this day. Labs can only create a few individual atoms of the element at any single time.

You can find mendelevium in the f-block of the periodic table, right after fermium. Mendelevium isotopes decay very quickly, making extensive chemical testing almost impossible. An isotope is a version of an element with a different number of neutrons.

The most stable isotopes break down mostly by capturing electrons and shooting out alpha particles. They eventually turn into lighter, slightly more stable elements over time.

Key facts

Field
General Chemistry
Symbol
Md
Atomic number
101
Atomic mass
[258] u
Category
Actinide
Year discovered
1955 at the University of California
Named after
Dmitri Mendeleev
Example
Scientists occasionally use the mendelevium-256 isotope in advanced radiotracer studies. A radiotracer is a radioactive chemical used to track how substances behave in experiments. Researchers use this specific isotope to study the chemical properties of very heavy elements. They carefully watch how mendelevium acts and bonds with other chemicals in liquid solutions. This helps them understand the complex rules governing the heaviest elements on the periodic table.

Frequently asked questions

How do modern laboratories produce mendelevium?

Scientists produce it one atom at a time by smashing high-energy alpha particles into einsteinium targets. They do this inside powerful machines called particle accelerators.

Does mendelevium have any practical commercial or medical uses?

No, it has no practical uses outside of basic scientific research. It decays too quickly, gives off intense radiation, and is far too difficult to make.

Related terms

Sources & references

By the Chemistry Dictionary editorial team · Reviewed August 8, 2026