chem001-chapter04-notes

chem001-chapter04-notes - CHEM 001 Lecture Notes, Prof....

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CHEM 001 Lecture Notes, Prof. Wei-Min Dai 25 Chapter 4 Nuclear Chemistry: The Heart of Matter Radioisotopes • Radioactive decay – Many isotopes are unstable • Radioisotopes – Nuclei that undergo radioactive decay – May produce one or more types of radiation Natural Radioactivity • Background radiation – What occurs from natural sources – >80% of radioactivity exposure Types of Radiation • Ionizing radiation – knocks electrons out of atoms or groups of atoms – Produces charged species – ions – Charged species that cause damage
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CHEM 001 Lecture Notes, Prof. Wei-Min Dai 26 Nuclear Equations • Elements may change in nuclear reactions • Total mass and sum of atomic numbers must be the same • MUST specify isotope Rn = radon; He = helium; Po = polonium Po He Rn 218 84 4 2 222 86 + α particles alpha decay Alpha Decay • Nucleus loses α particle – Mass decreases by 4 and atomic number decreases by 2 P + n Beta Decay • Nucleus loses β particle – No change in mass but atomic number increases n 1 0 p 1 1 e 0 -1 + Within the nucleus: P + n Positron Emission • Loses a positron ( β + ) – Equal mass but opposite charge of an electron – Decrease in atomic number & no change in mass p 1 1 n 1 0 e 0 +1 + Within the nucleus: e 0 +1 γ 0 0 e 0 -1 + 2 Positron emission with gamma radiation:
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CHEM 001 Lecture Notes, Prof. Wei-Min Dai 27 Electron Capture • Nucleus absorbs an electron and then releases an X-ray
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This note was uploaded on 02/14/2012 for the course CHEM 001 taught by Professor Wei-mindai during the Fall '08 term at HKUST.

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chem001-chapter04-notes - CHEM 001 Lecture Notes, Prof....

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