How Is Mendelevium Produced and Why Is It Important?
What is Mendelevium?
Mendelevium is a highly radioactive, synthetic element in the actinide series. It is denoted by the symbol Md and atomic number 101. It can only be produced by bombarding lighter elements with charged molecules. American chemists Bernard G Harvey, Stanley G Thompson, Albert Ghiorso, Glenn T. Seaborg and Gregory R Choppin discovered the element in 1955 at University of California, Berkeley. They discovered it by bombarding alpha particles (helium ions) with a minute amount of einsteinium-253. The element is named after the father of the periodic table and Russian chemist Dmitry Mendeleev.
The chemistry of Mendelevium isotopes is distinctive for the late actinides, with a majority of the +3 oxidation state but also a nearby +2 oxidation state. The most stable isotope is Mendelevium-258. It has a half-life of around 51.5 days. Later it decays to einsteinium-254 by the process of alpha decay or spontaneous fission hence all the isotopes of mendelevium have a shorter life. 16 isotopes of Mendelevium are acknowledged, with mass numbers from Md 245 to Md 260. All isotopes are radioactive.
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Properties of Mendelevium
Physical Properties
Atomic number 101
Atomic mass number- 258
Position in periodic table-Period 7, block- f, group- actinides
State at 200 C- Solid
Electron Configuration of gaseous state- [Rn] 5f13 7s2
Stablest isotope- Mendelevium-258
Oxidation states- +2, +3
Melting Point - 1100 K or 15210 F or 8270 C
The gravity and boiling point are still unknown
The Chemical Abstract Service registry number (CAS) is 7440-11-1
Key isotopes- 258Md, 260Md
Its colour is unknown but it is considered metallic or silvery white or grey.
Chemical Properties
Till date, chemical reactions are carried out only in solutions with +2 or +3 oxidation states. Though the +1 state has been reported to be found out but not yet confirmed.
It is trivalent in aqueous solution.
It forms insoluble fluorides and hydroxides that are condensed with trivalent lanthanide salts.
The mendelevium elutes during carbon-exchange bonding.
It has a smaller ionic radius than that of the previous actinide (Fermium) in the periodic table.
Mendelevium(III) can be reduced to Mendelevium(II) easily. It acts stable in aqueous solution.
It is neutral in water-ethanol solution and analogous or homologous to caesium.
It behaves like divalent elements when reduced.
On co crystallizing Mendelevium with chlorides, form mixed crystals with divalent elements.
It tends to decay.
It has 16 synthetic isotopes whose mass number lies between 245-260.
Production in Laboratories
Mendelevium is still produced in the same way as it was produced the first time in an all-night experiment. The lightest isotopes 245Md to 247Md are produced through the bombardment of Bismuth with heavy Argon ions in a 60-inch cyclotron.
Slightly heavier isotopes are produced by bombardment Plutonium with Carbon ions and Americium with Nitrogen ions in the cyclotron. The most stable 258Md isotope is produced by bombarding einsteinium with alpha particles.
The recoil momentum of produced Md takes it apart from the einsteinium target. Then it is brought on to a thin metal foil in a vacuum. This process eliminates the need for immediate chemical separation.
Md atoms are separated from metal foil by using fission products. Then Md atoms are trapped in a gaseous atmosphere, the jet of gas carries it along. Using the capillary tubes having potassium chloride aerosols in helium gas, Md atoms are transported over a short distance.
An alternative technique to isolate Mendelevium incorporates the discrete elution properties of Md from those of einsteinium and fermium.
The preliminary steps are the same as above, and engages HDEHP for abstraction chromatography, but coprecipitates the mendelevium with terbium fluoride instead of lanthanum fluoride. Then Chromium is introduced to the Mendelevium to condense it in hydrochloric acid with Zinc or Mercury
The solvent extraction takes place, and even though the tetravalent lanthanides and trivalent and actinides stay on the column, It is again oxidized to the +3 state using hydrogen peroxide and then isolated by elution with hydrochloric acid (to eliminate impurities and chromium) and finally hydrochloric acid (to extract the mendelevium).
It is also advisable to use a column of zinc and cationic amalgam, using 1 M hydrochloric acid as an eluent, reducing Mendelevium(III) to Md(II) where it behaves like the alkaline metals.
Isotopes of Md
The most stable Isotope after Md-256 is Md-257 and Md 260. All rest have a life span less than an hour.
The lifespan of Md isotopes shows growth after Md-245 but again decreases from Md-256.
Uses of Mendelevium
As it has a shorter life, it is produced in smaller quantities. It has no commercial use. It is mainly used for research purposes only.
The isotope 256Md is used to study the behaviour of mendelevium in aqueous solution.
It is used in the synthesis of other heavy atomic nuclei.
FAQs on Mendelevium: Detailed Guide to Properties, Isotopes & Uses
1. What are the main physical and chemical properties of Mendelevium?
Mendelevium (Md) is a synthetic, highly radioactive metal belonging to the actinide series. While its physical properties are not fully known due to the small quantities produced, it is predicted to be a solid at room temperature with a silvery-white or grey metallic appearance. Chemically, its most common oxidation state is +3, typical for late actinides. However, it also exhibits a uniquely stable +2 oxidation state in aqueous solutions, which is a key point of interest for researchers.
2. How is Mendelevium produced?
Mendelevium does not occur naturally and is produced artificially in minuscule amounts. The most common method involves bombarding a target of a lighter element with accelerated particles. Specifically, it was first synthesised by bombarding Einsteinium-253 (253Es) with alpha particles (helium ions) in a 60-inch cyclotron. This nuclear reaction produces isotopes of Mendelevium one atom at a time.
3. What are the uses of Mendelevium?
Due to its extreme rarity, high radioactivity, and short half-life, Mendelevium has no commercial or industrial applications. Its sole purpose is for basic scientific research. Scientists study Mendelevium to understand the chemical and physical properties of the heaviest elements, which helps in testing and refining theories of atomic structure and nuclear stability.
4. How many isotopes of Mendelevium are known, and which is the most stable?
There are 16 known isotopes of Mendelevium, with mass numbers ranging from 245 to 260. All of them are radioactive. The most stable isotope is Mendelevium-258 (258Md), which has a half-life of approximately 51.5 days. This relatively longer lifespan allows scientists a brief window to study its chemical properties.
5. What is the predicted electron configuration of Mendelevium (Md)?
The predicted electron configuration for Mendelevium, which has an atomic number of 101, is [Rn] 5f13 7s2. This configuration places it in the f-block's actinide series and is fundamental to understanding its chemical behaviour, including its common +3 and stable +2 oxidation states.
6. Why was Mendelevium named after Dmitri Mendeleev?
The element was named in honour of Dmitri Mendeleev, the Russian chemist renowned for creating the Periodic Table. The discovery team, led by Albert Ghiorso in 1955, chose this name to recognize Mendeleev's groundbreaking work in arranging elements by their properties. His periodic system was a guiding principle that enabled scientists to predict the existence and properties of undiscovered elements, including synthetic ones like Mendelevium.
7. Why is Mendelevium considered hazardous?
Mendelevium's primary hazard is its intense radioactivity. It decays by emitting energetic particles (like alpha particles) that can ionise and damage living tissue. Exposure to such radiation can disrupt cellular function, damage DNA, and increase the risk of cancer and other serious health issues. All work with Mendelevium is conducted in specialised hot cells to protect researchers from radiation exposure.
8. What makes Mendelevium's chemistry particularly interesting compared to other actinides?
The most fascinating aspect of Mendelevium's chemistry is its unusually stable divalent (+2) oxidation state in aqueous solution, alongside the more typical trivalent (+3) state of actinides. This deviation from the expected trend provides a crucial testing ground for theories about relativistic effects in heavy atoms. These effects influence electron orbitals and energies, and studying Mendelevium helps scientists understand how these rules apply at the extreme end of the periodic table.
