Bio 201 1st Edition Lecture 2 Outline of Last Lecture I. Brief Introduction to Biological ChemistryA. Covalent BondsB. ElectronegativityOutline of Current Lecture I. BondsA. HydrogenB. Van der Waal II. Acids and Bases, pH, Equilibria III. BuffersCurrent LectureI. Bonds (other than last weeks covalent and ionic bonds)A. Charge asymmetry is formed when covalently bonded atoms have small differences in electronegativity-In water, Oxygen takes some of Hydrogen’s electron density, resulting in a chargeasymmetry or a dipole-Dipoles (charge asymmetry) result in a polar molecule-Polar molecules contain atoms that attract opposite charge, the force holding these together is a Hydrogen Bond-Hydrogen bonds are not as strong as ionic, nor covalent bonds, but they are stronger then Van der Waal bondingB. Van der Waal bonds are the weakest of all, but when multiple combine they can be very strong.-When transient, weak dipoles in non-polar molecules interact they form Van derWaal bonds-Non-polar molecules are hydrophobic, or “water fearing”, therefore Van der Waal bonds can also be referred to as the hydrophobic effectII. Equilibria, Acids/Bases, and pHA. Equilibrium- a state in which both reactants and products exist but the total concentrations of reactants and products are no longer charging. This state is 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.indicated in a reaction by a double arrow. This means that a reaction can go both ways (reactants to products as well as products to reactants) at the same speed. For example, water is in equilibrium with itself, the reaction can occur both ways at the same speed. B. pH- refers to a scale that measures how basic, neutral, or acidic a molecule is. -When a pH is measured >7 (less than 7) the molecule is a base-When a pH is measured <7 (greater than 7) the molecule is an acid-Lastly, if a pH is measured to be exactly 7 the molecule is neutral-pH= -log [H+] for example when [H+] =10^-7 the pH is 7-Acid Dissociation- is the ability for a weak acid to partially dissociate (molecules in a chemical reaction split apart), while strong acids can fully dissociate-Functional groups (refer to Lecture 1) can also be acidic or basicIII. Buffers- have the ability to change pH when added to an acid or a base, any solution that minimizes changes in pH is a buffer. -LeChattelier’s Principle- when equilibrium experiences a change in concentration the equilibrium shifts to counteract that change-Weak acids (and weak bases) are
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