As the outer electron drops into the vacancy, it will emit energy. The loss of an inner shell electron leaves a vacancy that will be filled by one of the outer electrons. Cobalt-60 emits γ radiation and is used in many applications including cancer treatment:ġ9 40 K + -1 0 e ⟶ 18 40 Ar 19 40 K + -1 0 e ⟶ 18 40 ArĮlectron capture occurs when an inner shell electron combines with a proton and is converted into a neutron. The presence of a nucleus in an excited state is often indicated by an asterisk (*).
Gamma emission (γ emission) is observed when a nuclide is formed in an excited state and then decays to its ground state with the emission of a γ ray, a quantum of high-energy electromagnetic radiation. Consequently, the n:p ratio is decreased, and the daughter nuclide lies closer to the band of stability than did the parent nuclide. Emission of an electron does not change the mass number of the nuclide but does increase the number of its protons and decrease the number of its neutrons. Such nuclei lie above the band of stability. The beta particle (electron) emitted is from the atomic nucleus and is not one of the electrons surrounding the nucleus. The radiation produced during radioactive decay is such that the daughter nuclide lies closer to the band of stability than the parent nuclide, so the location of a nuclide relative to the band of stability can serve as a guide to the kind of decay it will undergo ( Figure 21.5).ĥ3 131 I ⟶ -1 0 e + 54 131 Xe or 53 131 I ⟶ -1 0 β + 54 131 Xe 53 131 I ⟶ -1 0 e + 54 131 Xe or 53 131 I ⟶ -1 0 β + 54 131 Xeīeta decay, which can be thought of as the conversion of a neutron into a proton and a β particle, is observed in nuclides with a large n:p ratio. The daughter nuclide may be stable, or it may decay itself. The unstable nuclide is called the parent nuclide the nuclide that results from the decay is known as the daughter nuclide. The spontaneous change of an unstable nuclide into another is radioactive decay. During the beginning of the twentieth century, many radioactive substances were discovered, the properties of radiation were investigated and quantified, and a solid understanding of radiation and nuclear decay was developed. Among them were Marie Curie (the first woman to win a Nobel Prize, and the only person to win two Nobel Prizes in different sciences-chemistry and physics), who was the first to coin the term “radioactivity,” and Ernest Rutherford (of gold foil experiment fame), who investigated and named three of the most common types of radiation. Describe common radiometric dating techniquesįollowing the somewhat serendipitous discovery of radioactivity by Becquerel, many prominent scientists began to investigate this new, intriguing phenomenon.Calculate kinetic parameters for decay processes, including half-life.Write and balance nuclear decay equations.Identify common particles and energies involved in nuclear decay reactions.Recognize common modes of radioactive decay.By the end of this section, you will be able to:
0 kommentar(er)
