1. Nuclear Chemistry & Radioactive Decay

2. Nuclear Chemistry Defined Changes occurring WITHIN the nucleus of an atom Atomic nuclei often emit particles or rays Atoms of one element are often converted into atoms of another element Can involve any of the subatomic particles Big energy changes

3. Radiation & Radioactivity Radiation: Radiation: the emission of nuclear particles by a radioactive substance Radioisotope: Radioisotope: An isotope of an element with an unstable nucleus Instability is caused by the imbalance of protons and neutrons in the nucleus

4. Radioactive Decay The process by which nuclear particles are emitted from the nucleus It reduces the amount of the substance that originally existed It is aimed at regaining stability in the nucleus by restoring a proper balance between protons and neutrons

6. There are 4 main types of Radioactive Decay 1. Beta decay – 1. Beta decay – “adds” a proton a. A beta particle is essentially an electron 2. Alpha decay – 2. Alpha decay – removes 2 protons & 2 neutrons 3. Positron emission – 3. Positron emission – emits a positively charged beta particle 4. Electron capture – 4. Electron capture – captures an electron to combine with a proton and make a neutron

7. Beta Decay Neutron releases a beta particle Atomic number increases by one. Mass number does not change

8. Radioactive Decay Rates Half-Life: Half-Life: The amount of time required for one-half of a radioisotope’s nuclei to decay into its products. Half-Life Formula(s): Half-Life Formula(s): Amount remaining = (initial amount)(1/2) n Amount remaining = (initial amount)(1/2) n Where n = the # of half-lives that have passedOR Amount remaining = (initial amount)(1/2) t/T Amount remaining = (initial amount)(1/2) t/T Where t = elapsed time and T = duration of half-life

9. Half-Life Calculation Example : Example : Iron-59 is used in medicine to diagnose blood circulation disorders. The half-life of Iron-59 is 44.5 days. How much of a 2.000-mg sample will remain after 133.5 days? Known information: Known information: Initial amount = Initial amount = 2.000-mg Elapsed time (t) = Elapsed time (t) = 133.5 days Half-life (T) = Half-life (T) = 44.5 days Formula to use: Formula to use: Amount remaining = (initial amount)(1/2) t/T Answer-.2500 mg

10. Nuclear Fission vs. Nuclear Fusion Nuclear Fission: the splitting of a nucleus into smaller fragments accompanied by the release of neutrons and LARGE amounts of energy.

11. Nuclear Fission vs. Nuclear Fusion Nuclear Fusion: the process of combining nuclei to produce a nucleus of greater mass, accompanied by HUGE amounts of energy.