CHEM 1061 1nd Edition Lecture 25 Outline of Last Lecture I. Monoatomic IonsII. Pseudo Noble Gas ConfigurationsIII. Transition ElementsIV. Trends in Atomic SizeV. Isoelectric IonsOutline of Current Lecture II. BondingIII. Ionic Bonding IV. Born-Haber Cyclea. examplesCurrent LectureBondingBonding is the favorable interaction that stabilizes or lowers the energy1) Ionic bonding2) Covalent Bonding3) Electronegativity4) Metallic BondingIonic Bonding Usually ionic bonding is between a metal and a nonmetalex: Na + Cl [Ne]3s(1) + [Ne]3s(2)3p(5)Na has one valence electron.Cl has seven valence electrons.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.Lewis Dot Symbol: # of dots = group #/ # of valence electrons Electron transfer happens. Na+ + Cl-[Ne] + [Ar]NaClOctet rule: outer shell of 8 electrons (same as noble gas configuration/ full shell)Lattice Energy: What holds ionic compounds togetherRepresented by Holattice1mol solid ionic compound to startNaCl(s) Na+(g) +Cl-(g) Separated ions in gaseous stateH for Hlattice = + (positive)it takes a lot of energy to pull a solid apart into ions. [endothermic put in energy]Born-Haber CycleAn application of Hess’s law.EXAMPLE: Born-Haber cycle for formation of LiFWhat is the Hlattice?Target Equation:Li(S) + ½ F2(g) LiF (s) H*f = -617 KJAny of the following equations can be set equal to the heat of formation equation. 1) Li(s) Li(g)H(sublimation) = 161 KJ2) 1/2F(2)(g) F(g)H = ½ bond energy = 79.5 KJ3) Li(g) Li+(g) + e-H = IE1 =520 KJ4) F(g) + e- F-(g)H = EA1 = -328 KJ5) LiF(s) Li+(g) + F-(g) H (lattice) = ????DO NOT add target equation into identifying equations once you know your target leave it alone!!Flip 5) because LiF is a product in the target. Change the H to be negative.Reactants: Li(s) + 1/2F(2)(g) + Li(g) + F(g) + Li+(g) + F-(g) + e-Products: Li(g) + F(g) + Li+(g) + e- + F-(g) + LiF(s) Only cancel out identical things. Caution on the anions and cations. Li(s) + ½ F(2)(g) LiF(s) [matches target]Add up H161 KJ + 79.5 KJ + 520 KJ + -328 KJ + - Hlattice = -617 KJ-617 KJ = 432.5 KJ + - Hlattice -1050 KJ = - Hlattice 1050 KJ Postive because the reaction is
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