[permalink] [id link]
The isotope < sup > 28 </ sup > Mg is radioactive and in the 1950s to 1970s was made commercially by several nuclear power plants for use in scientific experiments.
from
Wikipedia
Some Related Sentences
isotope and <
Actinium is found only in traces in uranium ores as the isotope < sup > 227 </ sup > Ac, which decays with a half-life of 21. 772 years, predominantly emitting beta particles.
Several unusual applications, such as a nuclear battery or fuel for space ships with nuclear propulsion, have been proposed for the isotope < sup > 242m </ sup > Am, but they are as yet hindered by the scarcity and high price of this nuclear isomer.
The second isotope < sup > 242 </ sup > Am was produced upon neutron bombardment of the already-created < sup > 241 </ sup > Am.
Upon rapid β-decay, < sup > 242 </ sup > Am converts into the isotope of curium < sup > 242 </ sup > Cm ( which had been discovered previously ).
The single primordial beryllium isotope < sup > 9 </ sup > Be also undergoes a ( n, 2n ) neutron reaction with neutron energies over about 1. 9 MeV, to produce < sup > 8 </ sup > Be, which almost immediately breaks into two alpha particles.
Primordial beryllium contains only one stable isotope, < sup > 9 </ sup > Be, and therefore beryllium is a monoisotopic element.
The ( α, 2n ) reaction induced by the irradiation yielded the < sup > 243 </ sup > Bk isotope and two free neutrons:
It is a synthetic element whose most stable known isotope, < sup > 270 </ sup > Bh, has a half-life of 61 seconds.
The GSI team further studied the reaction in 1989 and discovered the new isotope < sup > 261 </ sup > Bh during the measurement of the 1n and 2n excitation functions but were unable to detect an SF branching for < sup > 261 </ sup > Bh.
This reaction was studied for the first time in 2007 by the team at LBNL to search for the lightest bohrium isotope < sup > 260 </ sup > Bh.
Recently, the team at the Institute of Modern Physics ( IMP ), Lanzhou, have studied the nuclear reaction between americium-243 and magnesium-26 ions in order to synthesise the new isotope < sup > 265 </ sup > Bh
The only exception to the atomic mass of an isotope atom not being a natural number is < sup > 12 </ sup > C, which has a mass of exactly 12 by definition, because u is defined as 1 / 12 of the mass of a free neutral carbon-12 atom in the ground state.
IUPAC prefers that isotope symbols be written in superscript notation when practical, for example < sup > 12 </ sup > C and < sup > 235 </ sup > U. However, other notations, such as carbon-12 and uranium-235, or C-12 and U-235, are also used.
Calcium also has a cosmogenic isotope, radioactive < sup > 41 </ sup > Ca, which has a half-life of 103, 000 years.
The most abundant isotope, < sup > 40 </ sup > Ca, has a nucleus of 20 protons and 20 neutrons.
Mass-dependent differences in calcium isotope composition conventionally are expressed the ratio of two isotopes ( usually < sup > 44 </ sup > Ca /< sup > 40 </ sup > Ca ) in a sample compared to the same ratio in a standard reference material.
Mn-Cr isotope ratios reinforce the evidence from < sup > 26 </ sup > Al and < sup > 107 </ sup > Pd for the early history of the solar system.
One isotope of cadmium, < sup > 113 </ sup > Cd, absorbs neutrons with very high probability if they have an energy below the cadmium cut-off and transmits them otherwise.
They reported a 9. 40 MeV and a 9. 70 MeV alpha-activity and assigned the decays to the isotope < sup > 260 </ sup > Db or < sup > 261 </ sup > Db:
isotope and 28
It is a synthetic element ( an element that can be created in a laboratory but is not found in nature ) and radioactive ; the most stable known isotope, dubnium-268, has a half-life of approximately 28 hours.
Rubidium has only one stable isotope, < sup > 85 </ sup > Rb, with the isotope < sup > 87 </ sup > Rb, which composes almost 28 % of naturally occurring rubidium, being slightly radioactive with a half-life of 49 billion years — more than three times longer than the estimated age of the universe.
The reaction of berkelium-249 with nitrogen-14 was first studied in Dubna in 1977, and in 1985, researchers there confirmed the formation of the < sup > 260 </ sup > Rf isotope which quickly undergoes spontaneous fission in 28 ms:
While natural strontium is stable, the synthetic < sup > 90 </ sup > Sr isotope is present in radioactive fallout and has a half-life of 28. 90 years.
The Russian team's desire to use an element they could not access was due to the nature of the calcium beam: The isotope of calcium used in the beam, calcium-48, has 20 protons and 28 neutrons.
The fourth element, dubnium, has been synthesized in the laboratory, but it has not been found occurring in nature, with half-life of the most stable isotope, dubnium-268, being only 28 hours, and other isotopes even more radioactive.
< sup > 28 </ sup > Si ( the most abundant isotope, at 92. 23 %), < sup > 29 </ sup > Si ( 4. 67 %), and < sup > 30 </ sup > Si ( 3. 1 %) are stable.
isotope and is
In the universe, argon-36 is by far the most common argon isotope, being the preferred argon isotope produced by stellar nucleosynthesis in supernovas.
The second longest-lived isotope of astatine, astatine-211, is the only one currently having any commercial application, being employed in medicine to diagnose and treat some diseases via its emission of alpha particles ( helium-4 nuclei ).
Six astatine isotopes, with mass numbers of 214 to 219, are present in nature as the products of various decay routes of heavier elements, but neither the most stable isotope of astatine ( with mass number 210 ) nor astatine-211 ( which is used in medicine ) is produced naturally.
An atom is classified according to the number of protons and neutrons in its nucleus: the number of protons determines the chemical element, and the number of neutrons determines the isotope of the element.
The major isotope of berkelium, berkelium-249, is synthesized in minute quantities in dedicated high-flux nuclear reactors, mainly at the Oak Ridge National Laboratory in Tennessee, USA, and at the Research Institute of Atomic Reactors in Dimitrovgrad, Russia.
The berkelium-249 isotope emits low-energy electrons and thus is relatively safe to handle.
The isotope which is the easiest to synthesize is berkelium-249.
Its alpha radiation is rather weak – 1. 45 % with respect to the β-radiation – but is sometimes used to detect this isotope.
The second important berkelium isotope, berkelium-247, is an alpha-emitter, as are most actinide isotopes.
* The BCS theory reproduces the isotope effect, which is the experimental observation that for a given superconducting material, the critical temperature is inversely proportional to the mass of the isotope used in the material.
Ninety – four different chemical elements or types of atoms based on the number of protons are observed on earth naturally, having at least one isotope that is stable or has a very long half-life.
Whereas the mass number simply counts the total number of neutrons and protons and is thus a natural ( or whole ) number, the atomic mass of a single isotope is a real number.
In general, it differs in value when expressed in u for a given nuclide ( or isotope ) slightly from the mass number, since the mass of the protons and neutrons is not exactly 1 u, the electrons contribute a lesser share to the atomic mass as neutron number exceeds proton number, and ( finally ) because of the nuclear binding energy.
However, the atomic mass in u of pure isotope atoms is quite close ( always within 1 %) to its simple mass number.
isotope and radioactive
Each element has at least one isotope with an unstable nucleus that can undergo radioactive decay.
* Nuclear cardiology: The use of nuclear medicine to visualize the uptake of an isotope by the heart using radioactive sources.
By observing which areas of the brain take up the radioactive isotope, we can see which areas of the brain are more active than other areas.
The radioactive isotope caesium-137 has a half-life of about 30 years and is used in medical applications, industrial gauges, and hydrology.
A less accessible but rather efficient method is introduction of a radioactive isotope into the reaction and monitoring how it changes over time and where it moves to ; this method is often used to analyze redistribution of substances in the human body.
Self diffusion, exemplified with an isotopic tracer of radioactive isotope < sup > 22 </ sup > Na
Stable and radioactive isotope studies provide insight into the geochemical evolution of rock units.
This isotope of radioactive iodine used for ablative treatment is more potent than diagnostic radioiodine ( usually iodine-123 or a very low amount of iodine-131 ), which has a biological half life from 8 – 13 hours.
Helium-3 was hypothesized to be a radioactive isotope until helions were also found in samples of natural helium, which is mostly helium-4, taken both from the terrestrial atmosphere and from natural gas wells.
This explains why the radioactive isotope predominates in abundance compared to the stable one.
Naturally occurring lanthanum is composed of one stable (< sup > 139 </ sup > La ) and one radioactive (< sup > 138 </ sup > La ) isotope, with the stable isotope, < sup > 139 </ sup > La, being the most abundant ( 99. 91 % natural abundance ).
For example, a radioactive isotope lutetium-176 is used in nuclear technology to determine the age of meteorites.
All isotopes of lawrencium are radioactive ; its most stable known isotope is lawrencium-262, with a half-life of approximately 3. 6 hours.
In this case, the bismuth would present some minor radiation problems, as it is not quite as transparent to neutrons, and can be transmuted to a radioactive isotope more readily than lead.
To conduct the scan, a short-lived radioactive tracer isotope is injected into the living subject ( usually into blood circulation ).
All isotopes of radium are highly radioactive, with the most stable isotope being radium-226, which has a half-life of 1601 years and decays into radon gas.
Rhenium ( meaning: " Rhine ") was the last element to be discovered having a stable isotope ( other new radioactive elements have been discovered in nature since then, such as neptunium and plutonium ).
It is a synthetic element ( an element that can be created in a laboratory but is not found in nature ) and radioactive ; the most stable known isotope, < sup > 267 </ sup > Rf, has a half-life of approximately 1. 3 hours.
Radiometric dating ( often called radioactive dating ) is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates.
0.501 seconds.