What is Mendelevium definition properties isotopes and applications
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 Chemical Element Overview
1. What is Mendelevium?
Mendelevium (Md) is a synthetic radioactive element with atomic number 101 that belongs to the actinide series of the periodic table. It is a man-made element produced in particle accelerators and does not occur naturally on Earth. Mendelevium is classified as a transuranium element because its atomic number is greater than uranium (92).
2. What is the symbol and atomic number of Mendelevium?
The chemical symbol of Mendelevium is Md, and its atomic number is 101. The atomic number 101 means each atom of mendelevium contains 101 protons in its nucleus. This position places it in the f-block of the periodic table among the actinides.
3. Who discovered Mendelevium and when?
Mendelevium was first synthesized in 1955 by a team led by Albert Ghiorso at the University of California, Berkeley. It was produced by bombarding einsteinium-253 with alpha particles in a cyclotron. The element was named in honor of Dmitri Mendeleev, the creator of the periodic table.
4. How is Mendelevium produced?
Mendelevium is produced artificially by nuclear bombardment reactions in particle accelerators. One common synthesis reaction is:
- 253Es + 4He → 256Md + 1n
In this reaction, einsteinium-253 is bombarded with alpha particles (4He nuclei), forming mendelevium-256 and one neutron. All known isotopes of mendelevium are radioactive.
5. What group and period is Mendelevium in?
Mendelevium is located in the actinide series of the f-block in period 7 of the periodic table. Although sometimes associated with group 3, it is primarily classified as an actinide due to its filling of the 5f subshell. Actinides are heavy, radioactive elements with similar chemical behavior.
6. What is the electron configuration of Mendelevium?
The ground-state electron configuration of Mendelevium is [Rn] 5f13 7s2. This means it has a radon core followed by 13 electrons in the 5f subshell and 2 electrons in the 7s subshell. The partially filled 5f orbitals are responsible for its classification as an actinide element.
7. What are the common oxidation states of Mendelevium?
The most stable oxidation state of Mendelevium is +3. In aqueous chemistry, Md3+ behaves similarly to other trivalent actinide ions such as americium and curium. A less common +2 oxidation state has also been observed under strongly reducing conditions.
8. What are the physical properties of Mendelevium?
Mendelevium is a highly radioactive, metallic actinide element, but its physical properties are not fully characterized due to its short half-life and limited production. Predicted properties include:
- Silvery metallic appearance
- Solid at room temperature
- High density typical of actinides
Because only tiny amounts have been produced, most properties are estimated from periodic trends.
9. What are the isotopes of Mendelevium?
All isotopes of Mendelevium are radioactive, with mass numbers ranging approximately from 244 to 260. The most stable isotope is 258Md, which has a half-life of about 51 days. Most other isotopes have much shorter half-lives, often measured in hours or minutes.
10. What are the uses of Mendelevium?
Mendelevium has no commercial uses and is used only for scientific research. It is primarily studied to understand:
- The chemistry of actinide elements
- Nuclear structure and stability
- The behavior of heavy transuranium elements
Due to its rarity and radioactivity, mendelevium is handled only in specialized nuclear research laboratories.
