Seaborgium (Sg)

Seaborgium is a chemical element with the atomic number 106 in the periodic table. It’s a synthetically produced radioactive substance. Hence, it does not occur in any layer of Earth’s crust. 

Assumed to belong to the transition metals group of the periodic table, this transactinoid element is calculated to have a maximum of six valence electrons [Sg(VI)]. Apart from its use in scientific research, element 106 has no other practical use. 

Chemical and Physical Properties of Seaborgium

Atomic Number106
Atomic Weight-263.1186 g.mol-1
GroupTransition Metal
Period7 (d-block)
Physical StatePresumably solid at room temperature
Half-life3.3(10) milliseconds [2.9(+13−7) milliseconds] to 14 minutes
Melting PointUnknown
Boiling PointUnknown
Van der Waals RadiusUnknown
Ionic Radius
Most Characteristic Isotope271Sg
Electronic Shell[Rn] 5f¹⁴6d⁴7s²
The Energy of the First IonizationN/A
The Energy of the Second IonizationN/A
Discovery Date1974
Discovered BySoviet Nuclear Research/ U. of Cal at Berkeley
UsesIt has no significant commercial applications.
DescriptionSynthetic radioactive metal.
Crystal StructureUnknown
Covalent Radius
Atomic Radius
Atomic Volume
Name OriginNamed in honor of Glenn Seaborg, American physical chemist known for research on transuranium elements.
LocationUSSR/United States
Oxydation States

Seaborgium is one of the least studied chemical elements because there have been only a few atoms of it produced. This man-made element has the periodic table symbol Sg, atomic number 106, predicted atomic mass of 262.94 g.mol-1, and electron configuration [Rn] 7s25f146d4. According to the chemical calculations, the predicted atomic radius of seaborgium is 128 pm. 

The appearance, as well as both the physical and chemical properties of element 106, are yet to be studied. Based upon the scientific evidence on the element’s chemical properties that have been derived so far, seaborgium could be easily compared to the Group 6 elements of the periodic table:  chromium (Cr), molybdenum (Mo), and tungsten (W). 

All elements of this family are classified as transition (refractory) metals. Due to this, seaborgium is presumably a solid substance at room temperature.

How Was Seaborgium Discovered?

By bombarding lead-207 and lead-208 with ions of chromium-54 in a cyclotron, a group of researchers at the Joint Institute for Nuclear Research at Dubna, Russia, U.S.S.R, led by Georgy N. Flerov produced the first atom of the element 106 – the 259Sg isotope.

Several years later, in 1974, a team of scientists including Glenn T. Seaborg, Carol Alonso and Albert Ghiorso at the University of California, Berkeley, and E. Kenneth Hulet from the Lawrence Berkeley National Laboratory, achieved a new success by bombarding atoms of californium-249 with ions of oxygen-18 in a super-heavy ion linear accelerator. This chemical reaction produced the seaborgium-263 isotope with a half-life of about 1 second, and four free neutrons. 

Despite achieving the same result with different methods, and in different times, both teams of discoverers reported their scientific evidence in 1974 and shared the credits on the discovery of a new transuranium element – seaborgium (Sg). 

How Did Seaborgium Get Its Name?

Element 106 was named after the American chemist Glenn T. Seaborg. Seaborg was honored for his work on the isolation of chemical elements that are heavier than uranium has led to the discovery and synthesization of all other transuranium elements of the periodic table. In addition, Seaborg’s actinide concept transformed the periodic table. 

Before ‘seaborgium’ was accepted as the official name of element 106, it has been labeled with the temporary name ‘unnilhexium’, meaning ‘one-zero-six’ in Latin.

Where Can You Find Seaborgium?

There are only a few atoms of this extremely radioactive transuranium element produced in a strictly controlled laboratory environment. For this reason, seaborgium cannot be found anyplace else. 

Seaborgium in Everyday Life

In terms of its use, seaborgium is applied only in scientific research. According to the Seaborg Institute, the Los Alamos (LANL) and Lawrence Livermore (LLNL), together with the University of California, Berkeley (UCB), are the laboratories with the largest contribution in the research of actinide elements.

How Dangerous Is Seaborgium?

Being a highly radioactive substance, seaborgium can be harmful and pose great danger to the health of the scientists who study its properties or try to produce more atoms of this chemical element.

Environmental Effects of Seaborgium

Due to the fact that there are only several synthetically produced atoms of seaborgium, this chemical element cannot be found in the environment or considered as a hazardous substance upon the geological, biological, or aquatic systems.

Isotopes of Seaborgium

There are 13 forms of seaborgium observed so far. As this chemical element is highly radioactive, there are no stable isotopes. With a half-life of about 14 minutes, seaborgium-269 is the most stable isotope of element 106. Most of the other seaborgium isotopes have an extremely short half-life and decay within several milliseconds. 

While seaborgium-261 decays by electron capture (EC) into dubnium-261, the other isotopes of seaborgium undergo alpha decay or a spontaneous fission into rutherfordium (Rf)  isotopes. 


[n 1]

ZNIsotopic mass (Da)

[n 2][n 3]



[n 4]



Spin and


[n 5]

Excitation energy[n 5]
258Sg106152258.11298(44)#3.3(10) ms

[2.9(+13−7) ms]

259Sg106153259.11440(13)#580(210) ms

[0.48(+28−13) s]

260Sg106154260.114384(22)3.8(8) msSF (74%)(various)0+
α (26%)256Rf
261Sg106155261.115949(20)230(60) msα (98.1%)257Rf7/2+#
EC (1.3%)261Db
SF (.6%)(various)
262Sg[n 6]106156262.11634(4)8(3) ms

[6.9(+38−18) ms]

SF (92%)(various)0+
α (8%)[2]258Rf
263Sg[n 7]106157263.11829(10)#1.0(2) sα259Rf9/2+#
264Sg106158264.11893(30)#37 msSF(various)0+
265aSg106159265.12109(13)#8(3) sα261Rf 
265bSg16.2 sα261Rf 
266Sg[n 8]106160266.12198(26)#360 msSF(various)0+
267Sg[n 9]106161267.12436(30)#1.4 minSF (83%)(various) 
α (17%)263Rf
269Sg[n 10]106163269.12863(39)#14 min[1]α265Rf 
271Sg[n 11]106165271.13393(63)#2.4 minα (67%)267Rf3/2+#
SF (33%)(various)

Source: Wikipedia

List of Seaborgium Compounds 

By the yelp of chemical calculations, it has been predicted that seaborgium would possibly adopt the oxidation state of +6. 

The first chemical compound prepared with element 106 is SgO2Cl2. It has been studied in agreement with relativistic quantum chemical calculations since there’s a lack of scientific data on this synthetic element. 

5 Interesting Facts and Explanations

  1. In 1951, the American nuclear chemist Glenn Theodore Seaborg won the Nobel prize in Chemistry for his work on the new elements with atomic mass higher than 100. This advocate for world peace and nuclear proliferation contributed to the discovery of the following transuranium elements: plutonium, berkelium, californium, einsteinium, americium, curium, fermium, mendelevium, and seaborgium.
  2. Georgy N. Flerov of the Joint Institute for Nuclear Research at Dubna, Russia, U.S.S.R., announced the discovery of element 106 in June 1974. 
  3. International Union of Pure and Applied Chemistry (IUPAC) officially adopted the name ‘seaborgium’ with the symbol Sg on August 30th, despite the rule that an element could not be named after a living person. At that time, Seaborg was also one of the scientists in the American team working on the discovery of element 106. 
  4. The elements with atomic numbers higher than 100 are referred to as transfermium elements. 
  5. Produced by the chemical reaction 249Cf(18O,4N)263X, seaborgium underwent an alpha emission before decaying into rutherfordium. After this, element 106 decayed by alpha emission to nobelium, which in turn further decayed between daughter and granddaughter isotope via alpha decay mode.