Chemistry

Chemistry 1210: Introduction to General Chemistry Dr. Gina M. Florio 15 Nov. 2012 Jespersen, Brady, Hyslop Chapter 9 Chemical Bonding: General Concepts Ionic Bonds Ch. 9.2 Ionic bonds are the attraction between positive and negative ions in an ionic compound. e.g. NaCl An electron is transferred from the metal (Na) to the nonmetal (Cl): Ionic compounds form when metals and nonmetals react and they are held together by ionic bonds. Compounds (ionic and molecular) are formed due to a decrease (lowering) of the potential energy of system. Net energy change associated with the electron transfer reaction. So, why does NaCl (s) form at all? 2 Lattice Energy of Ionic Compounds Ch. 9.2 The energy needed to produce separated gaseous ions from one mole of the solid is the lattice energy:

Chemistry 1210: Introduction to General Chemistry Dr. Gina M. Florio 18 October 2012 Brady, Jespersen, Hyslop Chapter 7 Energy & Chemical Change Thermochemistry: the study of energy flow during a chemical reaction Ch. 7.1 Energy: the ability to do work; often measured as heat Kinetic Energy: the energy of motion; KE = ?mv2 Potential Energy: stored or positional energy; chemical energy (no simple eqn.) Conservation of Energy: 1. Energy cannot be created or destroyed 2. Energy is only converted from one form to another (KE ? PE) 3. Total energy of the universe (or an isolated system) is constant Thermochemistry: Basic Definitions Units of Energy 1 Joule (J) ? the KE possessed by a 2 kg object moving at a velocity of 1 m/s 1 cal = 4.184 J (exactly) 1 kcal = 4.184 kJ