CHEM 251 1st Edition Lecture 13 Outline of Last Lecture I. Clicker QuestionII. Metal Structure III. AlloysIV. Energy-The GridOutline of Current Lecture V. Clicker QuestionVI. Ionic vs Covalent BondingVII. Ionic CompoundsVIII. Fajans’ RulesIX. Charge DensityCurrent LectureX. Clicker Questiona. Predict the sigma bonding polarization of NaCli.XI. Ionic vs Covalent Bondinga. Electronegativity considerations predict a range of bonding propertiesi. Similar electronegativity = nonpolar covalentii. Large electronegativity difference = polar covalentiii. Extreme electronegativity imbalance = ionic b. Ionic bonds- little electron sharingThese 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.c.d. Structurei. Ionic-large network ii. Covalent-small moleculese. Melting pointi. Ionic-highii. Covalent-lowerf. Solubilityi. Ionic-highly water solubleii. Covalent-highly insolubleXII. Ionic compoundsa. Hard, brittleb. High melting pointsc. Conductive upon meltingd. Dissolve in water to give conductive solutionse. “salts” for shortf. neutral in overall charge but specific charges may vary g. compared to atoms…i. anions (addition of an electron) = larger than atoms1. Zeff smaller, more e-/e- repulsionii. Cations (removal of an electron) = smaller than atoms1. Zeff larger, less e-/e- repulsionh. Bonding – MO Theoryi.i. Hydrationi. Break apart when dissolved in waterii. Different bonding of water to cations andanionsiii. O donates e- to Na+ => dative bondiv. Cl donates e- to empty sigma* orbital on H(H bond)XIII. Fajans’ Rulesa. What determines the degree of covalency?i. More highly charged cations => more covalentii. Larger and more highly charge anions => more covalentiii. Cations lacking noble gas configuration => covalentXIV.Charge
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