Transuranium Elements

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What are Transuranic Elements?

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The chemical elements are the building blocks of nature. All substances are combinations of these elements. There are a total of 118 known chemical elements with the heaviest naturally occurring element being uranium with atomic number = 92.

All those chemical elements lie beyond uranium in the periodic table or those elements with atomic numbers greater than 92 are transuranium elements or transuranic elements. All of the transuranium elements are unstable, decaying radioactively, with half-lives that range from ten million years to just a fraction of a second.


The first attempt for the preparation of transuranium elements was made in the year 1934 in the city of Rome, where a team of Italian physicists headed by Fermi and Emilio Segrè bombarded uranium nuclei with free neutrons. Although transuranium species might have produced, the experiment resulted in the discovery of nuclear fission rather than the formation of new elements. Not until 1940 was a transuranium element first positively produced and identified, when two American physicists, Edwin Mattison McMillan and Philip Hauge Abelson, working at the University of California at Berkeley, exposed uranium oxide to neutrons from a cyclotron target. One of the resulting products was an element found to have an atomic number of 93. It was named neptunium.

Transformations in atomic nuclei can be represented by equations that balance all the particles of matter and the energy involved before and after the reaction. The above transformation of uranium into neptunium can be written as follows:

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Transuranic Elements


It has an atomic number of 93 and has an atomic mass of 237 which is present in the actinide series on the Periodic Table. It is found between uranium (92), the last of the natural elements, and plutonium (94).

  • It belongs to the actinide series and is named because of the chemical affinity similar to actinium (89).

  • Like plutonium and uranium, neptunium (237) is also an alpha emitter, which means after disintegration it emits a particle formed of two protons and two neutrons (similar to a helium nucleus). It then transmutes into protactinium 233 (element 91).

  • Neptunium is produced through the neutron bombardment of a uranium nucleus.

  • Having a critical mass of 73 kg, Neptunium is considered unstable in nuclear weapons. 

  • Neptunium with no major commercial uses is needed for research and exploratory work.


Plutonium is the second transuranium element with an atomic number of 94 and part of the actinide group of the periodic table. It was first produced in 1960. It was isolated and was used to create a nuclear bomb “Fat Man” which was dropped in Nagasaki during the world war. 

  • The combined effect of the atomic bomb’s impact and radioactive after-effects took the lives of around 80,000 people.

  • Plutonium is named after the planet Pluto similar to its predecessor neptunium which was after the planet Neptune. 

  • This element comprises four oxidation states and six allotropes. It reacts easily with hydrogen and nitrogen.

  • The metal gets warm during the process of alpha decay, to such an extent that it is possible to boil water when the element is present in large amounts.

  • Uranium is the main source to obtain Plutonium which is obtained by the irradiation of uranium in nuclear reactors. Plutonium is generally not found in nature.

  • Plutonium can form intermediate compounds and alloys with most of the metals.

  • Transuranium elements like Neptunium, Americium, Curium along Plutonium are a radiological hazard and must be handled carefully with precaution.

  • The resistivity of plutonium is high at room temperature. It is high even at low temperatures.

  • Plutonium increases in density when it melts by 2.5%, but it has very high surface tension and viscosity when near its melting point compared to other metals.


It is a human-made actinide element part of the periodic table with an atomic number of 95 and has no stable isotopes. It was named after America. It was discovered by Seaborg, Leon Morgan, Ralph James, and Albert Ghiorso in the year 1944 and isolated by B.B. Cunningham as the isotope.

  • Actinides contain 15 elements starting from actinium with atomic number 89, and extending to lawrencium with atomic number 103.

  • Americium-241 can find its application in very small quantities in household ionization smoke detectors. Americium is very similar to plutonium (Pu) in many ways. It plays a major role in nuclear power production as a decay product.

  • Due to the scarcity of Plutonium in making spacecraft batteries, Americium can be used as a viable replacement in the forthcoming years.


Curium is a hard radioactive metal with an atomic number of 96 and has the symbol Cm. This metal is artificially produced in nuclear reactors. It is an electropositive element and is also a chemically active substance, which can not be obtained naturally. This metal possesses some magnetic properties. As the temperature increases, the resistivity of the metal also increases. In 1944, Glenn Seaborg, Albert Ghiorso, and James discovered this metal and was named after Marie Curie and Pierre Curie.

  • The isotopes of curium can be used in power generation industries such as thermoelectric and thermionic converters.

  • This metal can be used in the X-ray spectrometer for quantitative analysis.

  • In medical applications, it is used as a power source.

  • One gram of curium can produce around 3 watts of thermal energy so, It is used in spacecraft applications.

  • It has its uses in the field of research industries as it is a radioactive element.

  • Curium is a hazardous metal, which can cause some health disorders when inhaled.

  • It can damage the liver and also causes breathing and gastrointestinal problems when ingested.

  • Rats, when injected with an isotope of curium, were observed to develop skeletal cancer.

  • The radiation, which is emitted by curium is likely to cause the destruction of the RBCs.

  • Improper disposal of curium can lead to several environmental issues. Curium can be found in nature in the form of oxides. The radiation generated through the metal can have many natural impacts.

  • Curium is an insoluble chemical, which can also fix soil particles.


It is a radioactive element having atomic number 97 and is the fifth transuranium discovered.

  • They can be traced in different parts of the planet where nuclear tests were conducted.

  • It is also a member of the actinide series in the periodic table.

  • Presently, it is not used biologically or for technological purposes.

  • It was used as the atmospheric nuclear weapons tests between 1945 and 1980.

  • Its isotopes can be used for basic scientific research.

  • The element’s mass numbers range from 235 to 254 and have about twenty isotopes.

  • Every isotope of the element is radioactive.


It is a radio metallic element with an atomic number 98 and is a member of the actinide group of the periodic table and was discovered by G.T Seaborg in the year 1950. It gets its name from the university and the state of California.

  • Californium is a good source of neutrons and due to this property, it is useful in a nuclear power plant as a neutron startup source.

  • It can also be used in the detection to trace elements in samples by using neutron activation analysis.

  • It can be used to treat many brain and cervical cancers.

  • It tarnishes gradually when exposed to air and readily attacked by steam and acids. 

  • There are many compounds that exhibit different kinds of properties Eg: Californium – 252 is a very strong emitter of neutrons.

  • The element is not available naturally on Earth’s crust. It can be found in nuclear facilities and research laboratories as it can be used in medical diagnosis and mineral prospecting.

  • The biological use of the element is not found. As a few compounds are extremely radioactive, it is considered to be hazardous to health. The greatest threat of radioactivity in our life is that it can damage the genetic makeup, the genetic pool of living beings which is cumulative over generations.


Einsteinium belongs to group 13 of the heavy transuranic elements found in the actinide series. It was first discovered after World War II in the year around 1952 as a trace element in the residue from the massive explosion of the hydrogen bomb. It neither exists in nature nor found in the Earth’s crust. It can be produced in small amounts by artificial natural transmutations of other radioactive elements than by an additional explosion of thermonuclear weapons.

  • It is a synthetic element and a part of the periodic table having the atomic number 99.

  • The element was named in honour of Albert Einstein and is produced through a chain of nuclear reactions that involves bombarding each isotope and then allowing isotope beta decay.

  • Einsteinium is the seventh transuranic elements of the actinide series. 

  • Einsteinium is a radioactive element and also a member of the actinide group of the periodic table. It reacts with the oxygen atom, steam, and acids but does not react with alkalies. Its preferred oxidation state is +3.

  • There are a total of 17 isotopes of einsteinium with mass numbers ranging from 241 to 257 and three known isomers. All Einsteinium is radioactive in nature and the longest-lived isotope among all is einsteinium-252 with a half-life of 472 days.

  • It also has some medical uses but they are not commercial.

  • It is used majorly to study radiation damage, targeted radiation medical treatments, and accelerated ageing.


Fermium is also a transuranic element and a member of the actinide series in the periodic table of elements. It was first discovered by Albert Ghiorso and others at New Mexico and the University of California at Berkeley in the radioactive fallout from a nuclear test in the Pacific Ocean. Till now not enough fermium has been made to analyze its chemical properties, but it is predicted that it would be a metal susceptible to attack by acids, steam, and air.

  • Fermium can be produced in very small quantities and does not have an extended half-life.

  • As fermium can be found in very small quantities and all of its isotopes have very short lives, there is no commercial use of this element.

  • The scientists use this element for research in expanding their knowledge on the rest of the periodic table.

  • The most stable isotope is fermium-257 has a half-life of around 100.5 days.

  • This isotope can be decayed into californium-253 with alpha decay or through spontaneous fission. It no longer exists naturally on earth crust but earlier it was known to have been produced in natural reactor deposits. Since it does not occur naturally so it has no health hazards, facts and effects. Today fermium can be obtained easily in microgram quantities by bombarding neutrons of plutonium inside a nuclear reactor. 


Mendelevium is a highly synthetic and radioactive metal that is placed in the periodic table with an atomic number of 101 and symbol Md. The metal is produced in very minute amounts. The metal is named after the father of the periodic table, Dmitri Mendeleev. It was first discovered in the year 1965 by G.T. Seaborg.

  • It is utilized for the purpose of scientific research and also to study the chemical properties of different elements and aqueous solutions by the use of the isotope.

  • It was obtained by bombarding einsteinium-253 with helium ions. The metal has one most stable isotope, mendelevium-258, which has a half-life of 51.5 days.

  • It decays into einsteinium-254 through the process of alpha decay or the process of spontaneous fission.

  • This metal has around 16 synthetic isotopes whose mass numbers lie between 245 to 260.

  • The metal exhibits similar characteristics to that of the elements of the actinide series, and it also possesses an oxidation state 3.

  • Mendelevium is said to be a highly radioactive metal known to be harmful when taken directly inside the body.


Nobelium is named after Alfred Nobel who was the inventor of dynamite. It is a man-made element that is made in low quantities. It is a part of the actinide series. Till now there are twelve isotopes that have been determined among them. Nobelium is highly radioactive in nature and is a synthetic metal. It can be produced directly by nuclear bombardment i.e. by irradiating a californium-249 target with carbon-12 ions.

  • They are generally difficult to detect. One can find this metal on the periodic table to the left of the actinide lawrencium and to the right of actinide mendelevium. 

  • Nobelium is a divalent metal. 

  • The behaviour of this metal can be better known only in an aqueous solution. It finds no other application than for scientific research.

  • Because it has a short half-life, it does not have any harmful effects on the environment also.


Lawrencium with atomic number 103 is represented in the periodic table with the symbol ‘Lr’.It was discovered in 1961.

  • It never occurs as a free element in nature and was created by accelerating subatomic particles that have been surrounded by a circle. 

  • Lawrencium is a radioactive transuranic element that can be synthesized from californium.

  • Lawrencium is not used due to its radioactive nature.

  • They are purely used for scientific research only.

  • Lawrencium is of not much use. They are purely used for scientific research only.

  • Isotopes of Lawrencium are radioactive. Its isotopes have a half-life of eleven hours and it is the longest-lived super-heavy to date.

  • Among all the isotopes only 12 isotopes are known with mass numbers 252, 262, and 266.

FAQ (Frequently Asked Questions)

Q1. What are Transuranic Elements?

Answer: All chemical elements in the periodic table beyond uranium or elements with atomic numbers greater than 92 are called transuranium elements.

Q2.  What is the Application of Uranium?

Answer: The isotope U-235 is essential because it can be split readily and yield a lot of energy under certain conditions. Therefore it is known as ‘fissile’ and uses the expression ‘nuclear fission.’

Q3: Write Some Properties of Uranium.

Answer: Uranium reacts with almost all nonmetals and their compounds except noble gases and the reactivity increases with rising in temperature.

It is easily dissolved in hydrochloric and nitric acid but with non-oxidizing acids, it reacts slowly.

It can be extracted from ores chemically and converted to uranium dioxide or other usable forms in the industry.

Finely divided uranium can react with cold water.

Uranium-235 undergoes fission when bombarded with slow-moving neutrons it divides into two smaller nuclei releasing nuclear binding energy and some neutrons.