AP Chemistry Chapter 8
8.1 A. Lewis symbols Lewis symbols B. Octet rule- every atom wants a full outer shell of electrons, that’s 8, to be more stable
8.2 Ionic bonding (salts) brittle solids, high melting point A. + - Na Cl transfer of electrons usu. metal with nonmetal B. Lattice NRG-NRG required to completely separate a mole of a solid ionic compound into gases ions.
Dogs teaching chemistry • http://www.youtube.com/watch?v=_M9khs87xQ8&sns=em
…Continue 8.2 1. E=kQ1Q2 d NRG increases as charge increases and distance decreases. C. electronic configuration of ions Fe = [Ar] 4s2 3d6 Fe+3 = [Ar] 3d5
8.3 A. size of ions 1. Metals-smaller, pos, lost electrons 2. Nonmetals- larger, neg, gained electrons B. Isoelectric series = same # e- 1. Increase nuclear charge (ENC) 2. Decrease ionic radius
8.4 A. Covalent bonding sharing of electrons 1. Usu. 2 nonmetals 2. Lewis structures B. Multiple bonds 1. O2 - double bond = 2 pair shared e- 2. N2 - triple bond = 3 pair of shared e- 3. single – longest bond triple – shortest bond 4. triple – strongest, highest bond NRG C. Metallic bond – sea of e-
8.5 I. Electronegativity – ability to attract shared e- A. trend F=4.0 B. Linus Pauling II. Bond Character > 1.67 ionic 0.20<1.67 polar covalent <0.20 nonpolar covalent
…Continue 8.5 III. Polarity A. polar – unsymmetrical molecule B. nonpolar – symmetrical molecule C. dipole – polar bond or molecule D. dipole moment – measure of polarity. 0dm = NP IV. NAMING
8.6 Drawing Lewis Structures I. Formal Charges = # val. E in isolated atom - #e assigned to the atom in the Lewis structure. OR F.C. = (val e- - bonds – unshared e-) Do not represent real charges.
8.7 A. Resonance Structure 1. More than one way to draw 2. Need double or triple bond that can move 3. All bond lengths are same, they average out.
…Continue 8.7 BOND ORDER 1 = single bond 2 = double bond 3 = triple bond B. benzene B.O. = 9 bonds = 1.5 6 spaces
8.8 Exception 1. NO2 – odd # of e- 2. BF3 – less than octet 3. PCl5 – expanded octet
8.9 Strengths of Covalent Bonds • Bond Enthalpy (bond NRG) – how easily are bonds broken. Always positive. • Enthalpy of Reactions = (bond broken – bonds formed) CH4 + Cl2 CH3Cl + HCl (pg. 326) 4C-H 4(413) 3C-H 3(413) Cl-Cl(242) H-Cl 431 C-Cl328 +1894 -1998 ΔH= - 104 kJ/mol • ΔH = reactants - products
Nitroglycerin • 4C3H5N3O9(l) 6N2(g) + 12CO2(g) + 10H2O(g) + O2(g) 4 moles of liquid makes 29 moles of gas!!