CHEM 2OA3 Lecture Notes - Methyl Group, Activation Energy, Cyclic Compound
7 Sep 2014
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Document Summary
Recall that electrons achieve a lower energy state when they occupy a bonding molecular orbital. Thus, breaking a bond requires an input of energy. For a bond to break, electrons in bonding mo must receive energy from their surroundings: specifically, surrounding molecules must transfer some kinetic energy to system (bond being broken) Homolytic bond cleavage generates two uncharged species, called radicals, each of which bears an unpaired electron. Heterolytic bond cleavage involves a two-headed curved arrow, generating ions. Energy required to break a covalent bond via homolytic bond cleavage is called the bond dissociation energy. Ho refers to bond dissociation energy when measured under standard conditions (where pressure is 1 atm and compound is in its standard state) Informally defined as measure of disorder associated with system. More accurately described in terms of probabilities. A process that involves an increase in entropy is said to be spontaneous: process can and will occur, given enough time.
