Nuclear decay, prediction

The nuclei of some elements are stable, but others decay the moment they are formed. Is there a pattern to the stabilities and instabilities of nuclei The existence of a pattern would allow us to make predictions about the modes of nuclear decay. One clue is that elements with even atomic numbers are consistently more abundant than neighboring elements with odd atomic numbers. We can see this difference in Fig. 17.11, which is a plot of the cosmic abundance of the elements against atomic number. The same pattern occurs on Earth. Of the eight elements present as 1% or more of the mass of the Earth, only one, aluminum, has an odd atomic number. 

Nuclear decay is a random process, yet it proceeds in a predictable fashion. To resolve this paradox, consider an everyday analogy. An unstable nucleus in a sample of radioactive material is like a popcorn kernel in a batch of popcorn that is being heated. When a kernel pops, it changes form. Similarly, an unstable nucleus changes form when it decays. 

Sometimes it is difficult to predict if a particular isotope is stable and, if unstable, what type of decay mode it might undergo. All isotopes that contain 84 or more protons are unstable. These unstable isotopes will undergo nuclear decay. For these large massive isotopes, we observe alpha decay most commonly. Alpha decay gets rid of four units of mass and two units of charge, thus helping to relieve the repulsive stress found in the nucleus of these isotopes. For other isotopes of atomic number less than 83, we can best predict stability by the use of the neutron to proton (n/p) ratio. 

A particular isotope may undergo a series of nuclear decays until finally a stable isotope is formed. For example, radioactive U-238 decays to stable Pb-206 in 14 steps, a majority of which are alpha emissions, as one might predict. 

Predict the particles and electromagnetic waves produced by different types of radioactive decay, and write equations for nuclear decays. 

Conversion of a radioactive parent to a single stable daughter, as occurs for is the simplest form of nuclear decay. Although it is impossible to determine when an individual radioactive nucleus will convert, decay rates become predictable for large populations of... 

Unlike chemical reaction rates, which are sensitive to factors such as temperature, pressure, and concentration, the rate of spontaneous nuclear decay cannot be changed. Because the decay of an individual nucleus is a random event, it is impossible to predict when a specific nucleus in a sample of a radioactive material will undergo decay. However, the overall rate of decay is constant, which allows you to predict when a given fraction of the sample will have decayed. 

Beta Decay Gamma Production Predicting Products of Nuclear Decay... 

Although a richness of information has been obtained, a number of open questions still remain. For elements which were chemically identified, like Rf or Sg, a more detailed study, both theoretical and experimental, should follow. Elements 109, 110 and 111 are still to be studied experimentally the prerequisites for their successful experimental studies should be similar to those of the lighter transactinides. These include the existence of isotopes long enough for chemical studies, knowledge of their nuclear decay properties, so that they can be positively identified, synthesis reactions with the highest possible cross sections and suitable techniques for their separation. For those elements, predictions of the chemical behaviour are a matter of future research. Especially difficult will be the accurate prediction of adsorption of the heaviest elements on various surfaces, or their precipitation from aqueous solutions by determining electrode potentials. For that, further developments in accurate calculational schemes are needed. More sophisticated methods are needed to treat weak interactions, which are important for physisorption processes. 

There are some nuclei of elements that the force cannot hold together, and the nuclei begin to disintegrate. A basic law of nature says that unstable materials may not exist naturally for long. Unstable materials must do whatever they can to achieve stability. Radioactive elements throw off particles from the nucleus to reach stability. This throwing-off of particles is called radioactivity the process is known as nuclear decay. This decay process is a random, spontaneous occurrence. There is no way that it can be shut off, nor is there any way to predict when a particular atom will begin to decay. 

Nuclear decay, the emission of radiation from a decaying atom, and the detection of emitted radiation by a detector are inherently random phenomena. Their occurrences cannot be predicted with certainty, even in principle, although they can be described probabilistically. The randomness of these processes causes the result of a radiation-counting measurement to vary when the measurement is repeated and thus leads to an uncertainty in the result, called the counting uncertainty. ... 

Predict nuclear stability and expected type of nuclear decay from the neutron-to-proton ratio of an isotope. (Section 21.2)... 

The mass-energy relationship can be used to predict the energy release in nuclear decay reactions, as illustrated in Example 17.3. 

The discovery and identification of element 101 (mendelevium, Md) was a landmark experiment in many ways [ 1 ]. It was the first new transuranium element to be produced and identified on the basis of one-atom-at-a-time chemistry and it is also the heaviest element (to date) to be chemically identified by direct chemical separation of the element itself. All of the higher Z elements have been first identified by physical/nuclear techniques prior to study of their chemical properties. In fact, one of the criteria for chemical studies is that an isotope with known properties be used for positive identification of the element being studied. Due to relativistic effects [1] chemical properties cannot be reliably predicted and a meaningful study of chemical properties cannot be conducted with both unknown chemistry and unknown, non-specific nuclear decay properties ... 

Ds is said to be chemically similar to platinum. Predicted details of the nuclear decay" suggest the alpha particles energies from Ds to be about 7.12 MeV, and the alpha... 

The analysis of steady-state and transient reactor behavior requires the calculation of reaction rates of neutrons with various materials. If the number density of neutrons at a point is n and their characteristic speed is v, a flux effective area of a nucleus as a cross section O, and a target atom number density N, a macroscopic cross section E = Na can be defined, and the reaction rate per unit volume is R = 0S. This relation may be appHed to the processes of neutron scattering, absorption, and fission in balance equations lea ding to predictions of or to the determination of flux distribution. The consumption of nuclear fuels is governed by time-dependent differential equations analogous to those of Bateman for radioactive decay chains. The rate of change in number of atoms N owing to absorption is as follows ... 

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