Physio Chem 150 Week 5
Physio Chem 150 Week 5 Chem 150
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This 4 page Class Notes was uploaded by Brianna S. on Sunday September 25, 2016. The Class Notes belongs to Chem 150 at Xavier University taught by Dr. Stroud in Fall 2016. Since its upload, it has received 61 views. For similar materials see Physiological Chemistry in Chemistry at Xavier University.
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Date Created: 09/25/16
Physiological Chemistry 150 Lecture Notes Week Five: 09/19 – 09/23 Definitions Chemical Reaction: involve unions, separations, and/or rearrangement of atoms Nuclear Reaction: Involve conversions of subatomic particles within the atoms o Isotopes may differ/ be distinguished by Nuclear changes Radioisotopes: emit radiation, unstable isotopes that undergo nuclear changes Radioactive Decay: occurs as an unstable (parent) nucleus converts into a stable (daughter) nucleus Examples: alpha decay, beta decay, gamma radiation and positron emission Alpha Decay Nucleus loses an alpha particle, Mass decreases by 4, atomic # decreases by 2 Example: Beta Decay Nucleus loses a beta particle, No change in mass, but the atomic # increases Example: Gamma Radiation Gamma energy, , is released from an unstable nucleus (indicated by “m” following the mass #), Net result is an energetically more stable isotope. Example: Positron Emission Loss of a positron, Decreases in atomic #, no change in mass Example: Electron Capture Nucleus absorbs an electron and then releases an X- ray Mass stays the same, the atomic # decreases Example: + X –ray Nuclear Transmission Conversion of one nucleus into another by high energy bombardment with a particle Radioisotopes are often used for medical purposes (radiation treatment) Radiation Protection Requires: Paper and clothing for alpha particles Lab coat or gloves for beta particles A lead shield or a thick concrete wall for gamma radiation o Limiting the amount of time spent near a radioactive source o Increasing distance from the source Measuring Radiation Curie = # of disintegrations per second Rem = radiation equivalent for man o Measures the effect on the person 1 rem = 1 rad x relative biological effectiveness o Relative Biological Effectiveness (RBE) Beta and Gamma rays have 1 RBE Alpha radiation has 20 RBE Rads - express the amount of energy associated with the radiation 1 rad = 1 x 10 J per Kg of tissue Biological Effects of Exposure to Radiation (REMs) Dose (0 to 25) No observable effect; possible genetic effect Dose (25 to 100) Temporary decrease in number of WBCs Dose (100 to 200) Diarrhea (mild radiation sickness), vomiting, strong decrease in WBCs Dose (500) Death in half of the population Uses for Radioactive Nuclides 1. Food Processing (Irradiation) a. To prevent spoilage b. Irradiation kills most of the microorganisms that promote spoilage, increasing shelf life c. Gamma radiation is used because it passes through the food and does not make them radioactive 2. Medical Imaging a. Positron Emission Tomography (PET scan) i. Uses positron emitters with a short half life ii. Positrons combine with electrons after emission to produce gamma rays, which are then detected by computers, creating a three dimensional image of the organ b. Computed Tomography (CT scan) i. Uses X rays, not gamma rays, essentially the same process as the PET scan 3. Treatment of Disease a. Cobalt – 60 emits gamma rays used in Chemo treatment for cancer 4. Carbon Dating a. A substance is checked for the emission of Carbon – 11 and the amount present indicates the age of the substance Half Life The time required for half of a sample to decay or convert Allows for enough time to detect the isotope without extended chances for causing harm Modern Periodic Table Arranges elements in order by atomic number Though there are exceptions, the properties of elements tend to vary in a regular, systematic way Groups or Families ten to behave similarly (vertical columns) Periods are the horizontal rows on the periodic table The majority of the table is metals Metals: malleability, ductility, good conduction of heat and electricity Non-Metals: opposite of chemical and physical properties, insulators (brittle, powders or gases), non-conducting insulators Metalloids: Intermediate, semiconductors Periodic trend: a pattern of behavior that occurs with order or position on the periodic table o Ex: atomic number, atomic mass State the increase or decrease of the trend by: o Left to right o Right to left o Up or down o Top or bottom Ionization Energy Energy required to remove one of the valence (outermost) electrons Increases going left to right, but decreases going from top to bottom
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