Radioactive elements atomic transformation

An alplia p uticle is an energetic helium nucleus. The alplia particle is released from a radioactive element witli a neutron to proton ratio tliat is too low. The helium nucleus consists of two protons and two neutrons. The alplia particle differs from a helimn atom in that it is emitted witliout any electrons. The resulting daughter product from tliis tj pe of transformation lias an atomic number Uiat is two less tluin its parent and an atomic mass number tliat is four less. Below is an e. aiiiple of alpha decay using polonium (Po) polonium has an atomic mass number of 210 (protons and neutrons) and atomic number of 84. 

Within only two years of Soddy and Rutherford s papers on atomic transformation as the mechanism for radioactivity, writers of popular fiction did indeed make the shift from cathode rays pulling an unknown element from the moon to radium emissions and other such atomic technologies causing alchemical transmutation—and similarly fretted about the consequences to the gold-standard economy of the West. Rider Haggard s Ayesha The Return of She (1904-05) was noteworthy, as we have mentioned, because... 

They realized that the particles emitted by radioactive elements as they decay are in fact little bits of the atomic nuclei. By expelling them, the nucleus alters the number of protons it contains, and so it becomes the nucleus of a different element. Alpha decay carries off two protons and two neutrons (a helium nucleus), and so it converts one element to a slightly lighter element two columns earlier in the Periodic Table. Beta decay transforms a neutron into an electron (which is emitted) and a proton (which stays in the nucleus) - so the atomic number increases and the element moves one column further across the Periodic Table. Niels Bohr and Soddy formulated this rule, which was called the radioactive displacement law. 

In order to end up with an element that was not in the reactants, the particles in the nucleus of an atom—the protons and neutrons—would have to change. This is a different type of reaction, called a nuclear reaction. Some nuclear reactions occur naturally in elements that are described as radioactive. The nuclei of radioactive elements are unstable. Since they are unstable, they can fall apart and give off subatomic particles. Eventually, through a process called radioactive decay, these unstable elements are transformed into a stable (non-radioactive) element. When an atom of one element is changed into an atom of another element through a nuclear reaction, it is called transmutation. 

Since the nucleus undergoing (i decay is usually contained in an atom or a molecule, the /J decay is accompanied by rearrangement of the corresponding electron shell. The f decay results in the formation of a positive molecular ion in which the initial radioactive nucleus has transformed into a nucleus of the element shifted one square to the right in the periodic table. In the case of fi+ decay, the daughter ion is charged negatively, and the radioactive nucleus is replaced by a nucleus of the element shifted one square to the left in the periodic table.1 Namely... 

In order to use the perturbation theory it is necessary that the state vectors in the matrix element Eq. (8) belong to the spectrum of the unperturbed Hamiltonian H0 only. However, this is usually not so, since, in p decay, the initial particles are not the same as the final products of the reaction the initial molecule containing the radioactive atom transforms into a different molecule besides, the ft electron and the neutrino appear. One of the ways to describe the initial and final states using only the H0 Hamiltonian is to use the isotopic spin formalism for both the nucleons and the leptons (/ electron and neutrino). In the appendix (Section V) we present the wave functions of the initial and the final states together with the necessary transformations, which one can use to factorize the initial matrix element Eq. (8) into the intranuclear and the molecular parts. Here we briefly discuss only the approximations necessary for performing such a factorization. 

Radioactive Decay Radioactive elements are made up of atoms whose nuclei are unstable and give off atomic radiation as part of a process of attaining stability. The emission of radiation transforms radioactive atoms into another chemical element, which may be stable or may be radioactive such that it undergoes further decay. 

Because strontium is an element, its atoms do not degrade by environmental processes such as hydrolysis or biodegradation. However, radioactive strontium will be subject to radioactive decay and transformation to other elements. Eventually, all of the radioactive strontium will be transformed into stable zirconium by the process of radioactive decay (see Section 4.2) ... 

In 1898, in Cambridge, England, a New Zealander, Ernest Rutherford, demonstrated that there were at least two different types of radiation with different penetrating power. He called these alpha and beta radiation. He subsequentiy worked at McGill University in Montreal, Canada, and found more radioactive elements different types of radium and thorium, and actinium. He proposed that these were links in chains of radioactive materials, called the transformation theory. Rutherford and his colleague, Frederic Soddy, described that the rate of decay of radioactive elements were characteristic of the element, and came to be known as half-life. Decay follows the law of probability. Over a given period of time, each atom has a certain probability of decaying, a process that results from the random movements of the subatomic components of the radioactive atoms. This was the first instance in physics of a truly unpredictable phenomenon. The decay of a radioactive atom was probabilistic. 

On the basis of this evidence, Rutherford and Soddy in 1902 put forward their disintegration hypothesis. They proposed that radioactive elements were undergoing spontaneous transformation into new elements, and therefore the atoms of radioactive elements were breaking down into new atoms. Within the space of five years the Daltonian concept of the chemical atom had undergone a radical change. Not only had the existence of subatomic particles (electrons) been demonstrated, but also transmutation was shown to be a natural phenomenon. In their paper of 1902 Rutherford and Soddy also demonstrated that the decay of a radioactive substance followed an exponential law. 

Atoms with the same number of protons but a different number of neutrons are called isotopes. To identify an isotope we use the symbol E, where E is the element s atomic symbol, Z is the element s atomic number (which is the number of protons), and A is the element s atomic mass number (which is the sum of the number of protons and neutrons). Although isotopes of a given element have the same chemical properties, their nuclear properties are different. The most important difference between isotopes is their stability. The nuclear configuration of a stable isotope remains constant with time. Unstable isotopes, however, spontaneously disintegrate, emitting radioactive particles as they transform into a more stable form. 

Isotopes. Toward the end of Mendeleev s life a growing body of evidence began to challenge his conception of the nature of tiie elements. Several revolutionary discoveries in physics showed that atoms were, in fact, reducible and that there was a sense in which all elements are composed of the same primary matter protons, neutrons, and electrons. Most alarmingly, there was even evidence to suggest that certain elements could be transformed into others through radioactivity. 

Neutron activation analysis (NAA) is a technique for the qualitative and/or quantitative determination of atoms possessing certain types of nuclei. Bombarding a sample with neutrons transforms some stable isotopes into radioactive isotopes measuring the energy and/or intensity of the gamma rays emitted from the radioactive isotopes created as a result of the irradiation reveals information on the nature of the elements in the sample. NAA Is widely used to characterize such archaeological materials as pottery, obsidian, chert, basalt, and limestone (Keisch 2003). 

Two of these isotopes, carbon-12, the most abundant, and carbon-13 are stable. Carbon-14, on the other hand, is an unstable radioactive isotope, also known as radiocarbon, which decays by the beta decay process a beta particle is emitted from the decaying atomic nucleus and the carbon-14 atom is transformed into an isotope of another element, nitrogen-14, N-14 for short (chemical symbol 14N), the most common isotope of nitrogen ... 

Chemical forms with at least one radioactive atomic nucleus are radioactive substances. The capability of atomic nuclei to undergo spontaneous nuclear transformation is called radioactivity. Nuclear transformations are accompanied by emission of nuclear radiation (Severa and Bar 1991). The average number of nuclei that disintegrate per unit time (= activity) is directly proportional to the total number of radioactive nuclei. The time for 50% of the original nuclei to disintegrate (= half-life or Tb 1/2) is equal to In 2/decay constant for that element (Kiefer 1990). Radiations... 

Rutherfordium - the atomic number is 104 and the chemical symbol is Rf. The name derives from the English physicist Ernest Rutherford who won the Nobel prize for developing the theory of radioactive transformations. Credit for the first synthesis of this element is jointly shared by American scientists at the University of California lab in Berkeley, California under Albert Ghiorso and by Russian scientists at the JINR (Joint Institute for Nuclear Reactions) lab in Dubna, Russia under Georgi N. Flerov. The longest half-life associated with this unstable element is 10 minute Rf. 

---