BCH 119S Lecture Notes - Lecture 1: Chemical Polarity, Gibbs Free Energy, Ionic Bonding

• School: UT-Austin
• Department: Biochemistry
• Course: BCH 119S
• Professor: Jeffrey Barrick

Document Summary

Most biomolecules include only: h, c, n, o, p, & s. Enthalpy: making and breaking covalent bonds/ionic interactions; can calculate from bond energies. Entropy: changes in degrees of freedom (# possible configurations of a system); more degrees of freedom are more favorable. Activation energy: determines how fast equilibrium is approached. Biology uses a lot of weak non-covalent interactions to do interesting things. Water is extremely polar (electrons are delocalized) and has ionizable hydrogens. Polar and charged molecules are highly soluble in water. C-c and c-h bonds are nonpolar and not soluble in water b/c not electronegative enough. Amphiphatic=polar and nonpolar parts in the same molecule. Epsilon: deals with how polar the water is. H20 weakens electrostatic interactions b/c dipoles in hydration shells shield each charge. Major intermolecular forces: electrostatic forces (van der waals/london dispersion force) Instantaneous induced dipole-dipole attraction; very weak charge or polar; larger e- clouds more polarizable;