CHAPTER 20 - NUCLEI AND NUCLEAR POWER

Abstract

This chapter explains the terms, such as “proton,” “neutron,” “isotope,” “atomic number,” “mass number,” and “atomic mass unit”. The composition and the behavior of all ordinary matter depends on four basic units-electrons, protons, neutrons, and photons. The chapter describes the binding energy of a nucleus, and how the shape of the binding energy curve shows that energy is released in the processes of fission and fusion. Exothermic nuclear reactions release energy as the mass decreases while the endothermic nuclear reactions require energy input as the mass increases. Fission of uranium or plutonium takes place when a neutron is absorbed and the process releases two or three neutrons on an average. The chapter explains the proton–proton chain. When the release of energy by the proton–proton reactions begins, the contraction ceases and the size of the star is stabilized. The abundances of the elements in the universe are explained in terms of nuclear reactions that take place in stars. Exploding stars return these elements to space where they become incorporated in later-forming second-generation stars.