Types of Nuclear Decay

Another difference between nucleons and electrons is that nucleons pair whenever possible. Thus, even if a particular energy level can hold more than two particles, two particles will pair when they are present. Thus, for two particles in degenerate levels, we show two particles as II rather than II. As a result of this preference for pairing, nuclei with even numbers of protons and neutrons have all paired particles. This results in nuclei that are more stable than those which have unpaired particles. The least stable nuclei are those in which both the number of neutrons and the number of protons is odd. This difference in stability manifests itself in the number of stable nuclei of each type. Table 1.3 shows the numbers of stable nuclei that occur. The data show that there does not seem to be any appreciable difference in stability when the number of protons or neutrons is even while the other is odd (the even-odd and odd-even cases). The number of nuclides that have odd Z and odd N (so-called odd-odd nuclides) is very small, which indicates that there is an inherent instability in such an arrangement. The most common stable nucleus which is of the odd-odd type is 147N. 

We have already stated that the majority of known nuclides are unstable and undergo some type of decay to produce another nuclide. The starting nuclide is known as the parent and the nuclide produced is known as the daughter. The most common types of decay processes will now be described. 

When the number of neutrons is compared to the number of protons that are present in all stable nuclei, it is found that they are approximately equal up to atomic number 20. For example, in 402oCa 

Beta (—) decay ( ). When we consider 146C, we see that the nucleus contains six protons and eight neutrons. This is somewhat rich in neutrons, so the nucleus is unstable. Decay takes place in a manner that decreases the number of neutrons and increases the number of protons. The type of decay that accomplishes this is the emission of a (3 particle as a neutron in the nucleus is converted into a proton. The (3 particle is simply an electron. The beta particle that is emitted is an electron that is 

The ejected electron did not exist before the decay, and it is not an electron from an orbital. One common species that undergoes 3 decay is 146C, 

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There are three forms of radioactivity (Table 35.1) arising from three main types of nuclear decay ... 

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

Electron capture is a rare type of nuclear decay in which an electron from the innermost energy level (the Is — see Chapter 3) is captured by the nucleus. This electron combines with a proton to form a neutron. The atomic number decreases by one, but the meiss number stays the same. The foUowdng equation shows the electron capture of Polonium-204 (Po-204) ... 

Tlie kind of trcuisformation tliat will take place for any given radioactive element is a function of the type of nuclear instability as well as the mass/eiiergy relationship. Tlie nuclear instability is dependent on the ratio of neutrons to protons a different type of decay will occur to allow for a more stable daughter product. The mass/energy relationship stales tliat for any radioactive transformation(s) the laws of conservation of mass tuid tlie conservation of energy must be followed. 

The equation for the decay of a nucleus (parent nucleus - daughter nucleus + radiation) has exactly the same form as a unimolecular elementary reaction (Section 13.7), with an unstable nucleus taking the place of a reactant molecule. This type of decay is expected for a process that does not depend on any external factors but only on the instability of the nucleus. The rate of nuclear decay depends only on the identity of the isotope, not on its chemical form or temperature. 

What is the difference between radioactive decay processes and other types of nuclear reactions ... 

There are at present 116 known chemical elements. However, there are well over 2000 known nuclear species as a result of several isotopes being known for each element. About three-fourths of the nuclear species are unstable and undergo radioactive decay. Protons and neutrons are the particles which are found in the nucleus. For many purposes, it is desirable to describe the total number of nuclear particles without regard to whether they are protons or neutrons. The term nucleon is used to denote both of these types of nuclear particles. In general, the radii of nuclides increase as the mass number increases with the usual relationship being expressed as... 

Gamma emission is the release of high-energy, short-wavelength photons, which are similar to x-rays. The representation of this radiation is y. Gamma emission commonly accompanies most other types of radioactive decay, but we normally do not show it in the balanced nuclear equation since it has neither appreciable mass nor charge. 

Consider the nuclei 15C, 15N, and 150. Which of these nuclei is stable What types of radioactive decay would the other two undergo Calculate the binding energy difference between 15N and 150. Assuming this difference comes from the Coulomb term in the semiempirical binding energy equation, calculate the nuclear radius. 

In almost all of the previous examples, we have looked at nuclear reactions that occur by spontaneous decay. There are other types of nuclear reactions that can occur, known as transmutation reactions. These reactions can be induced by forcing a reaction between the nucleus of an element and nuclear particles (such as neutrons), or nuclei. Ernest Rutherford carried out the first transmutation by bombarding nitrogen-14 nuclei with alpha particles. This resulted in the production of oxygen-17 and a proton, as shown below ... 

A) Identify the type of radioactive decay that oxygen-14 will undergo, and write a balanced nuclear equation for the process. 

Types of Radioactive Decay and Balancing Nuclear Equations... 

There are three main types of radioactive decay alpha particle emission, beta particle emission, and the emission of gamma radiation. When an unstable isotope undergoes radioactive decay, it produces one or more different isotopes. We represent radioactive decay using a nuclear equation. Two rules for balancing nuclear equations are given below. 

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

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