21.1+Radioactivity


 * Nucleons:** particles that make up the nucleus (protons and neutrons)
 * Isotopes:** elements with the same atomic number but a different atomic mass
 * Nuclide:** a nucleus with a specified number of protons and neutrons
 * Radionuclides:** radioactive nuclei
 * Radioisotopes:** atoms containing radioactive nuclei (radionulcides)


 * Most nuclei found in nature are stable
 * Radionuclides are unstable and spontaneously emit particles and electromagnetic radiation
 * by emitting particles of electromagnetic radiation, the unstable nucleus transforms into a more stable nucleus


 * __Types of Radioactive Decay__**
 * 1) Alpha Radiation
 * 2) Beta Radiation
 * 3) Gamma Radiation


 * Alpha Radiation**
 * Produces alpha particles
 * Alpha particles: Helium-4 nuclei (⁴ 2 He)
 * EX: 238 92 U --> 234 90 Th + ⁴ 2 He
 * Through alpha radiation, they nucleus undergoes radioactive decay


 * Beta Radiation**
 * Produces beta particle
 * Beta particles: high speed electrons emitted by an unstable nucleus
 * Represented by ⁰ -1 e
 * 0 represents the small mass of the electron
 * -1 represents the negative charge
 * Beta emission converts neutrons to protons
 * EX: 131 53 I --> 131 54 Xe + ⁰ -1 e


 * Gamma Radiation**
 * Produces gamma rays
 * Gamma rays: high energy photons (electromagnetic radiation of a very short wavelength)
 * Gamma radiation does NOT change atomic number or mass number
 * Represented by
 * Represents energy lost by the atom
 * Usually not shown when writing nuclear equations


 * Positron Emission**
 * Positron: particle that has the same mass of an electron by the opposite charge
 * EX: 11 6 C --> 11 5 B + ⁰ 1 e
 * Positron emission causes the atomic number to decrease by 1


 * Electron Capture**
 * Nucleus capture electron from the surrounding electron cloud
 * EX: 81 37 Rb + ⁰ -1 e (orbital electron) --> 81 36 Kr
 * The electron is consumed rather than absorbed, therefore the electron goes on the reactants side of the nuclear equation


 * REFERENCE**

Brown, Theodore L., and H. Eugene LeMay. Chemistry: The Central Science. Upper Saddle River, NJ: Pearson Prentice Hall, 2008. Print.