Types of Radioactive Decay Kinetics of Decay Nuclear Transmutations Nuclear Chemistry Types of Radioactive Decay Kinetics of Decay Nuclear Transmutations

Remember the Nucleus Remember that the nucleus is comprised of the two nucleons, protons and neutrons. The number of protons is the atomic number. The number of protons and neutrons together is effectively the mass of the atom.

Isotopes Not all atoms of the same element have the same mass due to different numbers of neutrons in those atoms. There are, for example, three naturally occurring isotopes of uranium: Uranium-234 Uranium-235 Uranium-238

Radioactivity: Kinetic Stability It is common for some nuclides of an element to be unstable, or radioactive. We refer to these as radionuclides. They can spontaneously decay emitting electromagnetic radiation and particles .

Types of Radioactive Decay

Alpha Decay Alpha decay is the loss of an -particle (a helium nucleus), results in more stable iosotope. He 4 2 -particle = U 238 92  234 90 He 4 2 +

Beta Decay Beta decay is the loss of a -particle (a high energy electron).  −1 e or I 131 53 Xe 54  + e −1

e C B e Positron Emission 1 Some nuclei decay by emitting a positron, a particle that has the same mass as but opposite charge to that of an electron. C 11 6  B 5 + e 1

Gamma Emission  This is the loss of a -ray, which is high-energy radiation that almost always accompanies the loss of a nuclear particle.

Electron Capture (K-Capture) p. 878 Addition of an electron to a proton in the nucleus is known as electron capture or K-capture. The result of this process is that a proton is transformed into a neutron. p 1 + e −1  n

Summary Table 21.3 p. 879