O bohrium is a synthetic element of Group 7 of the Periodic table, with an atomic number of 107. Its synthesis is credited to the German laboratories of the Helmholtz Center for Research on Heavy Ions. (GSI), from the city of Darmstadio, Germany, and its name was given in honor of the famous physicist Danish Niels Bohr.
Bohrium has a little-known chemistry, but it is already known that it behaves like the lighter elements of Group 7, rhenium and technetium, on some specific occasions. As its most stable isotope is only 17 seconds old and its synthesis is very complicated, little is known about this element.
See too: Bohr's atomic model — the first atomic model to use concepts from quantum mechanics
Summary about bohrium
It is a synthetic chemical element located in Group 7 of the Periodic Table.
It was first synthesized in 1981 by the Gesellschaft für Schwerionenforschung (GSI) in Darmstadium, Germany.
It is a radioactive element.
Chemically, it is speculated that it resembles the other elements chemicals lightest of its group, rhenium and technetium.
Like other transactinides, it suffers from low stability and the difficulty of synthesizing considerable samples of its own for studies.
bohrium properties
Symbol: BH
Atomic number: 107
Atomic mass: 264 c.u.
Electronic configuration: [Rn] 7s2 5f14 6d5
Most stable isotope:267Bh (17 second half-life)
Chemical series: Group 7, transactinides, superheavy elements
bohrium characteristics
Bohrium, as well as the other transactinides (elements with atomic number greater than 103), is a radioactive element. Six isotopes of this element are known, with mass 267 being the most stable, with about 17 seconds of half life (the time required for the amount of the element to halve).
Bohrium suffers from the same problem as other transactinides: the low production rate, either in quantity or in speed. In these elements, what is known as the chemistry of only one atom, which, in itself, makes the experiments more complex, since adaptations in terms of calculations are necessary.
We must remember that most of the equations are established for systems with at least two atoms. Add this to the fact that bohrium isotopes have a short half-life, which makes further studies about its nature unfeasible.
As a Group 7 element, bohrium is expected to have a chemical behavior similar to of rhenium and dthe technetium, lighter elements of this group. For example, bohrium has been found to form oxychlorides, BhO3Cl, as well as rhenium and technetium.
Read too: Dubnium — another synthetic radioactive element with a low production rate
Obtaining bohrium
The chemistry of transactinides is complicated to do. As one of these elements, bohrium issynthesized with particle accelerators, in which ionic species collide with heavy elements. However, its detection (proof) is also another challenge.
When formed, the radioactive element begins to decay and show alpha emissions and emissions beta. Thus, one must evaluate the radioactive decay of the atom formed or even be able to identify atomic species that may arise from these nuclear reactions, as in a puzzle.
Another hurdle is the half-life of transactinide isotopes. As they are usually short, in the range of seconds, an amount in the range of a few atoms or even a single atom is commonly obtained.
For bohrium, its most stable isotope, 267, was obtained through the bombardment of berkelium-249 with neon-22 ions.
\({_97^{249}}Bk+{_10^{22}}Ne\rightarrow{_107^{267}}Bh+4{_0^1}n\)
Precautions with bohrium
It is not yet possible to produce Bh on a large scale. So, the risks associated with this element are linked to the effects of radiation. However, in a controlled laboratory, these risks are anticipated and thus minimized.
Know more: Vanadium — chemical element whose world reserves exceed 63 million tons
history of bohrium
The transactinids are at the center of a troubled dispute that took place between 1960 and 1970, during another episode of the Cold War, the so-called War of the Transfers: the race for the synthesis of elements with atomic number above 103. In this unbridled dispute, the laboratories were involved: Joint Institute for Nuclear Research, in the city of Dubna, Russia; Lawrence Berkeley National Laboratory in Berkeley, California; and Gesellschaft für Schwerionenforschung (GSI, better translated as Helmholtz Center for Research on Heavy Ions), in Darmstadium, Germany.
However, in the case of the bohrium, the disputes were less intense. For example, for this element, the Berkeley group of scientists was not involved in the discovery. The Dubna group, led by Yuri Oganessian, was unable to prove the synthesis of element 107.
In this way, bohrium only was detected and confirmed by the German GSI group, led by scientists Peter Ambrüster and Gottfried Münzenberg, in 1981. Using the cold fusion technique, developed by Oganessian in the 1970s, the scientists were able to detect decays relative to the isotope 262 of element 107 through the following reaction:
\({_83^{209}}Bi+{_24^{54}}Cr\rightarrow{_107^{262}}Bh+{_0^1}n\)
The name Bohrian refers to the historical Danish scientist Niels Bohr. At first, the Americans requested that the name for element 107 be Nielsbohrium, in order to avoid a strong resemblance to the element boron.
However, in 1997, the International Union of Pure and Applied Chemistry (IUPAC) officially named element 107 bohrium.
Solved exercises on bohrium
question 1
Bohrium is a synthetic element with atomic number 107. Its most stable isotope has atomic number 267. How many neutrons are present in the 267 isotope of Bh?
A) 107
B) 160
C) 162
D) 164
E) 267
Resolution:
Alternative B
The number of neutrons can be calculated using the following formula:
A = Z + n
where A is the number of pasta atomic, Z is the atomic number (numerically equal to the number of protons), and n is the number of neutrons.
Substituting the values, we have:
267 = 107 + n
n = 267 - 107
n = 160
question 2
The half-life of the most stable isotope of the chemical element bohrium (Bh, Z = 107) is only 17 seconds. How long, in seconds, does it take for a sample of this Bh isotope to have only 1/16 of its initial mass?
A) 17 seconds
B) 34 seconds
C) 51 seconds
D) 68 seconds
E) 85 seconds
Resolution:
Alternative B
At each half-life, the mass of the Bh isotope drops by half. So, assuming the initial mass is equal to m:
After a half-life (17 seconds), the remaining mass of Bh is m/2.
After another 17 seconds (totaling 34 seconds), the mass becomes m/4.
After 51 seconds from the start of the experiment, the mass becomes m/8.
In this way, 1/16 of the initial mass will only be obtained after 68 seconds from the beginning of the experiment.
By Stefano Araújo Novais
Chemistry teacher
