Radioactive isotopes artificial

Symbol P At. wt. 30.9738 At. no. 15 CAS [7723-14-0] valences 3, 5 position in the periodic table group VB, along with nitrogen, arsenic, antimony and bismuth natmal isotope P radioactive isotopes (artificial) ... 

For the naturally occurring elements, many new artificial isotopes have been made, and these are radioactive. Although these new isotopes can be measured in a mass spectrometer, this process could lead to unacceptable radioactive contamination of the instrument. This practical consideration needs to be considered carefully before using mass spectrometers for radioactive isotope analysis. 

Few of the naturally occurring elements have significant amounts of radioactive isotopes, but there are many artificially produced radioactive species. Mass spectrometry can measure both radioactive and nonradioactive isotope ratios, but there are health and safety issues for the radioactive ones. However, modem isotope instmments are becoming so sensitive that only very small amounts of sample are needed. Where radioactive isotopes are a serious issue, the radioactive hazards can be minimized by using special inlet systems and ion pumps in place of rotary pumps for maintaining a vacuum. For example, mass spectrometry is now used in the analysis of Pu/ Pu ratios. 

It is not necessary that there be two isotopes in both the sample and the spike. One isotope in the sample needs to be measured, but the spike can have one isotope of the same element that has been produced artificially. The latter is often a long-lived radioisotope. For example, and are radioactive and all occur naturally. The radioactive isotope does not occur naturally but is made artificially by irradiation of Th with neutrons. Since it is commercially available, this last isotope is often used as a spike for isotope-dilution analysis of natural uranium materials by comparison with the most abundant isotope ( U). 

Plutonium (Pu) is an artificial element of atomic number 94 that has its main radioactive isotopes at 2 °Pu and Pu. The major sources of this element arise from the manufacture and detonation of nuclear weapons and from nuclear reactors. The fallout from detonations and discharges of nuclear waste are the major sources of plutonium contamination of the environment, where it is trapped in soils and plant or animal life. Since the contamination levels are generally very low, a sensitive technique is needed to estimate its concentration. However, not only the total amount can be estimated. Measurement of the isotope ratio provides information about its likely... 

Many artificial (likely radioactive) isotopes can be created through nuclear reactions. Radioactive isotopes of iodine are used in medicine, while isotopes of plutonium are used in making atomic bombs. In many analytical applications, the ratio of occurrence of the isotopes is important. For example, it may be important to know the exact ratio of the abundances (relative amounts) of the isotopes 1, 2, and 3 in hydrogen. Such knowledge can be obtained through a mass spectrometric measurement of the isotope abundance ratio. 

All isotopes of technetium (Z = 43) are unstable, so the element is not found an Avhere in the Earth s crust. Its absence left a gap in the periodic table below manganese. The search for this missing element occupied researchers for many years. It was not until 1937 that the first samples of technetium were prepared in a nuclear reactor. In fact, technetium was the first element to be made artificially in the laboratory. To date, 21 radioactive isotopes of technetium have been identified, some of them requiring millions of years to decompose. 

Radioisotope—An unstable or radioactive isotope of an element that decays or disintegrates spontaneously, emitting radiation. Approximately 5,000 natural and artificial radioisotopes have been identified. 

In essence, NAA involves converting some atoms of the elements within a sample into artificial radioactive isotopes by irradiation with neutrons. The radioactive isotopes so formed then decay to form stable isotopes at a rate which depends on their half-life. Measurement of the decay allows the identification of the nature and concentration of the original elements in the sample. If analysis is to be quantitative, a series of standard specimens which resemble the composition of the archaeological artifact as closely as possible are required. NAA differs from other spectroscopic methods considered in earlier chapters because it involves reorganization of the nucleus, and subsequent changes between energy levels within the nucleus, rather than between the electronic energy levels. 

The number of protons is unique to the element but most elements can exist with two or more different numbers of neutrons in their nucleus, giving rise to different isotopes of the same element. Some isotopes are stable, but some (numerically the majority) have nuclei which change spontaneously - that is, they are radioactive. Following the discovery of naturally radioactive isotopes around 1900 (see Section 10.3) it was soon found that many elements could be artificially induced to become radioactive by irradiating with neutrons (activation analysis). This observation led to the development of a precise and sensitive method for chemical analysis. 

ISOTOPES Cs-133 is the only stable isotope of cesium, and it makes up all of the naturally occurring cesium found in the Earth s crust. In addition to Cs-133 there are about 36 radioactive isotopes of Cs, most of which are artificially formed in nuclear reactors. All are produced in small numbers of atoms with relatively short half-lives. The range of Cs isotopes is from Cs-113 (amu = 112.94451) to Cs-148 (amu = 147.94900). Most of these radioisotopes produce beta radiation as they rapidly decay, with the exception of Cs-135, which has a half-life of 3x10 yr, which makes it a useful research tool. Cs-137, with a half-life of 33 years, produces both beta and gamma radiation. 

All the other eight Isotopes are radioactive and artificially produced with half-lives ranging from Be-8 = 0.067 seconds to Be-14 = 1.6x 10 years. 

ISOTOPES There are 30 isotopes of manganese, ranging from Mn-44 to Mn-69, with only one being stable Mn-55 makes up 100% of the element in the Earth s crust. All the other isotopes are artificially radioactive with half-lives ranging from 70 nanoseconds to 3.7x10 years. Artificial radioisotopes are produced in nuclear reactors, and because most radioactive isotopes are not natural, they do not contribute to the elemenfs natural existence on Earth. 

ISOTOPES There are 38 isotopes of zinc, ranging in atomic weights from Zn-54 to Zn-83. Just four of these are stable, and those four, plus one naturally radioactive isotope (Zn-70) that has a very long half-life (5x10+ years), make up the element s existence on Earth. Their proportional contributions to the natural existence of zinc on Earth are as such Zn-64 = 48.63%, Zn-66 = 27.90%, Zn-67 = 4.10%, Zn- 68 = 18.75%, and Zn-70 = 0.62%. All the other isotopes are radioactive and artificially produced. 

ISOTOPES There are 50 Isotopes of Yttrium. Only one Is stable (Y-89), and It constitutes 100% of the element s natural existence on Earth. The other Isotopes range from Y-77 to Y-108 and are all produced artificially In nuclear reactions. The radioactive Isotopes have half-lives ranging from 105 nanoseconds to 106.65 days. 

ISOTOPES Zirconium has 37 isotopes, ranging from Zr-79 to Zr-110. Four of them are stable, and one is a naturally radioactive isotope, with a very long half-life. All five contribute to the element s natural existence on Earth. The stable isotopes are the following Zr-90 = 1.45%, Zr-91 = 11.22%, Zr-92 = 17.15%, and Zr-94 = 17.38%. The one natural radioactive isotope is considered stable Zr-96, with a half-life of 2.2 x 10+ years, contributes 2.80% to zirconium s total existence on Earth. All of the other isotopes are artificially radioactive and are produced in nuclear reactors or particle accelerators. They have half-lives ranging from 150 nanoseconds to 1.53 x 10+ years. 

Zirconium-95 is the most important of the artificial radioactive isotopes of zirconium. It is placed in pipelines to trace the flow of oil and other fluids as they flow through the pipes. It is also used as a catalyst in petroleum-cracking plants that produce petroleum products from crude oil. 

ISOTOPES There are 47 isotopes. None are stable and all are radioactive. Most are produced artificially in cyclotrons (particle accelerators) and nuclear reactors. The atomic mass of its isotopes ranges from Tc-85 to Tc-118. Most of technetium s radioactive isotopes have very short half-lives. The two natural radioisotopes with the longest half-lives—Tc-98 = 4.2x10+ years and Tc-99 = 2.111 xl0+ years—are used to establish technetium s atomic weight. 

The major characteristic of technetium is that it is the only element within the 29 transition metal-to-nonmetal elements that is artificially produced as a uranium-fission product in nuclear power plants. It is also the tightest (in atomic weight) of all elements with no stable isotopes. Since all of technetiums isotopes emit harmful radiation, they are stored for some time before being processed by solvent extraction and ion-exchange techniques. The two long-lived radioactive isotopes, Tc-98 and Tc-99, are relatively safe to handle in a well-equipped laboratory. 

ISOTOPES There are 42 isotopes of palladium, ranging from Pd-91 to Pd-124. All but six are radioactive and artificially produced in nuclear reactors with half-lives ranging from 159 nanoseconds to 6.5x10+ years. The six stable isotopes of palladium and their proportional contribution to their existence in the Earth s crust are as follows Pd-102 = 1.02%, Pd-104 = 11.14%, Pd-105 = 22.23%, Pd-106 = 27.33%, Pd-108 = 26.46%, and Pd-110= 11.72%. 

ISOTOPES There are 52 isotopes of cadmium. Forty-four are radioactive and artificially produced, ranging from Cd-96 to Cd-131. Of these 52 isotopes, there are five stable isotopes plus three naturally occurring radioactive isotopes with extremely long half-lives that are considered as contributing to the element s natural occurrence in the Earth s crust. The three naturally radioactive isotopes (Cd-106, Cd-113, and Cd-116) are the longest known beta emitters. They are two million years older than when the solar system was formed about 4.5 billion years ago. The five stable isotopes and their proportional contributions to the elemenfs existence on Earth are as follows Cd-108 = 0.89%, Cd-110 = 12.49%, Cd-111= 12.80%, Cd-112 = 24.13%, and Cd-114 = 28.73%. 

ISOTOPES There are a total of 54 isotopes of gold, only one of which is stable Au-197, which accounts for the element s total natural existence on Earth. The remaining 53 isotopes are radioactive, are artificially produced in nuclear reactors or particle accelerators, and have half-lives ranging from a few microseconds to a few seconds to a few hours to a few days. 

ISOTOPES There are 46 Isotopes of xenon. Nine of these are stable. Two of the stable Isotopes are radioactive, but with half-lives long enough to be considered stable. They are Xe-124 (1.1 x lO+ years) and Xe-136 (3.6x 10+ ° years). The 47 manmade artificial radioactive Isotopes have half-lives ranging from 150 nanoseconds to 11.9 days. 

ISOTOPES There are a total of 45 Isotopes of europium. Two are considered stable and account for 100% of the europium found on Earth Eu-151 (47.81%) and Eu-153 (52.19%). All the other 53 Isotopes are radioactive and artificially produced, primarily through electron capture. 

Radioactive isotopes can be classified as being either artificial or natural. Only the latter are of interest in geology, because they are the basis for radiometric dating... 

Symbol Ce atomic number 58 atomic weight 140.115 a rare-earth metal a lanthanide series inner-transition /-block element metaUic radius (alpha form) 1.8247A(CN=12) atomic volume 20.696 cm /mol electronic configuration [Xe]4fi5di6s2 common valence states -i-3 and +4 four stable isotopes Ce-140 and Ce-142 are the two major ones, their percent abundances 88.48% and 11.07%, respectively. Ce—138 (0.25%) and Ce—136(0.193%) are minor isotopes several artificial radioactive isotopes including Ce-144, a major fission product (ti 284.5 days), are known. 

Symbol Rb atomic number 37 atomic weight 85.468 a Group I (Group 1) alkali metal element electron configuration [Kr] 5si valence -i-l atomic radius 2.43A ionic radius, Rb+ 1.48A atomic volume 55.9 cc/g-atom at 20°C ionization potential 4.177 V standard electrode potential Rb+ + e Rb, E° = -2.98V two naturally-occurring isotopes, Rb-85 (72.165%) and Rb-87 (27.835%) Rb-87 radioactive, a beta emitter with a half-bfe 4.88xl0i° year twenty-seven artificial radioactive isotopes in the mass range 74—84, 86, 88-102. 

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