BIOL 1103 1st Edition Lecture 3 Outline of Last Lecture II Historical Figures in Science III Cell Theory and the cell s parts IV Bonds Outline of Current Lecture V Hydrogen Bonds and Polarity VI Isotopes VII Water Molecules and Basics of pH Current Lecture 1953 marked the beginning of modern biology with the discovery of the double helix DNA Hydrogen bonds polarity o Hydrogen bond attraction between hydrogen atoms with a partial positive charge and a partial negative charge attraction between polar molecules o Nonpolar molecules have symmetric charges o If a molecule is nonpolar it will not dissolve in water o Electrons are shared equally between nonpolar molecules Isotopes o Ionic bonds gain or loss of an electron o Isotopes atoms that have the same atomic number but differ in atomic mass because they have a different number of neutrons o Radioactive isotope any of several species of same element with unstable nuclei Carbon 14 is the best element for dating things Free radical atom or molecule that has a single unpaired electron in outer shell Water and pH o In a salt water mixture for example Solute what is being dissolved salt Solvent what is doing the dissolving water Solution homogeneous mixture salt water o Living things are 75 95 water These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o o o o o o o o o o o o Earth s surface is 71 water Human body holds 66 water weight Water molecules bead up because of their polarity Water molecules stick together and form a liquid state because of hydrogen bonds Temperature can cause water molecules to move so fast that they break off from each other and form gas Ice water molecules bounded by hydrogen bonds that are stable Polar water molecules separate sodium and chloride and that s why it dissolves Attraction separation dispersion pH is a measure of hydrogen ion concentration 7 on pH scale is neutral water Hydrogen and hydroxide ions in equilibrium in water that is 25 degrees Celsius 7 basic blood 7 acidic our stomachs
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