19.1 - The Nature of Nuclear Reactions

• Radioactivity exists in all elements with an atomic number greater than 83.

  • The isotope of polonium 210 (210 84Po), for example, decays spontaneously to 206 82Pb by emitting a particle.

  • Nuclear transmutation is a type of radioactivity caused by the bombardment of nuclei by neutrons, protons, or other nuclei.

• An electron in or out of an atomic orbital is represented by the symbol 1 0 e.

• Although physically identical to any other electron, the sign 1 0 denotes an electron that originates from a nucleus rather than an atomic orbital.

  • Although the positron has the same mass as the electron, it has a positive charge.

19.2 - Nuclear Stability

• The nuclear binding energy, which is the energy required to break apart a nucleus into its component protons and neutrons, is a quantitative measure of nuclear stability.

• Studies of nuclear characteristics revealed that the masses of nuclei are always less than the sum of the nucleon masses, giving rise to the concept of nuclear binding energy.

  • The protons and neutrons in a nucleus are collectively referred to as nucleons.

  • The mass defect is the difference between the mass of an atom and the sum of the masses of its protons, neutrons, and electrons.

19.3 - Natural Radioactivity

• A radioactive nucleus' disintegration is frequently the start of a radioactive decay series, which is a series of nuclear processes that eventually leads to the production of a stable isotope.

• The principal types of radiation are the α (or duplicated helium nuclei, He2+) particles; β particles (or electrons); ć rays which are very short wave-length (0 nm to 10−4 nm).

• Gaseous argon-40 accumulation is used to measure the age of a sample.

  • Argon-40 is trapped in the mineral grid and can only escap when it melts.

• When a potassium-40 atom decays in a mineral decay the process of analyzing a mineral sample in the laboratory is therefore melting.

  • With a mass spectrometer, the amount of argon 40 can be easily measured.

19.4 - Nuclear Transmutation

• The so-called transuranium elements, which have atomic numbers greater than 92, have been synthesized thanks to particle accelerators.

• The so-called transuranium elements, elements with atomic numbers above 92, were able to be synthesised by particular accelerators.

  • It was first prepared in 1940 with Neptune (Z = 93).

• Since then there have been a synthesis of 25 other transuranium elements.

  • The radioactive isotopes of all of these elements.

• The transuranium elements reported and some reactions through which they have been formed are listed in Table 19.4.

19.5 - Nuclear Fission

• Nuclear fission is the splitting of a heavy nucleus into smaller intermediate-mass nuclei and one or more neutrons.

• A nuclear chain reaction, which is a self-sustaining succession of nuclear fission processes, is made feasible by this feature.

• When the amount of fissionable material equals or exceeds the critical mass, which is the minimal mass of fissionable material required to initiate a self-sustaining nuclear chain reaction.

• Before they may be utilized to induce nuclear disintegration, they must be slowed down for higher efficiency.

  • Scientists utilize moderators, which are chemicals that can limit the kinetic energy of neutrons, to achieve this purpose.

• A breeder reactor uses uranium fuel, but it creates more fissionable materials than it consumes, unlike a typical nuclear reactor.

19.6 - Nuclear Fusion

• Nuclear fusion, which involves the joining of tiny nuclei to form larger ones, is relatively waste-free in comparison to nuclear fission.

• Fusion reactions are often referred to as thermonuclear reactions since they occur exclusively at extremely high temperatures.

• Molecules cannot exist at temperatures of roughly 100 million degrees Celsius, and most or all atoms are stripped of their electrons.

  • Plasma is a state of matter that consists of a gaseous mixture of positive ions and electrons.

19.7 - Uses of Isotopes

• Tracers are isotopes, particularly radioactive isotopes, that are used to track the route of an element's atoms in a chemical or biological process.

• The isotope is used to label the S atoms when this sequence is started by elementary sulfur enriched by the radioactive sulfur-35 isotope.

• The two sulfur atoms in S2O3 2– clearly do not, as is the case, represent structural equivalence.

• An important advantage of tracing radioactive isotopes is that they can be easily detected.

  • Even in very small quantities, photographic methods or instruments known as counters can detect their presence

19.8 - Biological Effects of Radiation

• Particles and gamma rays both can take electrons from atoms and molecules in their path, resulting in the production of ions and radicals.

  • Radicals are molecular fragments with one or more unpaired electrons; they are frequently unstable and reactive.

• Beta particles penetrate more, but less than gamma rays, than alpha particles.

  • The gamma rays are extremely short and high energy wavelengths.

• Moreover, since the shielding of materials as easily as alpha and beta particles cannot be stopped because the charge is free.

• However, if alpha and beta emitters are ingested, their damage effects become significantly worsened, as organ radiation in the closest range is constantly damaged.

  • For example, a beta emitter, Streontium-90, may substitute calcium in bones, where it is most damaging.