Introduction to Molecule Structures
Introduction to Molecule Structures CHEM-1070-30
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This 4 page Class Notes was uploaded by Nina Kalkus on Monday November 16, 2015. The Class Notes belongs to CHEM-1070-30 at Tulane University taught by Schmehl, Russell in Fall 2015. Since its upload, it has received 16 views. For similar materials see General Chemistry I in Chemistry at Tulane University.
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Date Created: 11/16/15
Chapter 9, Sections 1-6: Periodic Properties Radii Trends: atomic: decrease across a period (left to right on a row) *up until noble gases, hard to measure their radii ionic: positive charge- radius decreases relative to the neutral negative charge- radius increases relative to the neutral *radius increases as you go down in families (down the column) Ionization Energies: atomic ionization: when you go to the next n level, IE drops He IE (v) Ne N O Be Li B Na 2 Z (nuclear charge) ionic ionization: Na ---> isoelectronic with Ne + Na has much higher IE than Na Mg --> isoelectronic with Na (in general, harder to ionize 1+ ions) Example: IE(kJ) 1 st 2nd 3rd 4th Na: 495 4562 --- --- Mg: 737 1451 7733 --- Al: 577 1817 2745 11,580 ElectronAffinities: Eg+ e --------> E g Either be ΔH==> positive or negative Examples: Li: EA(ElectronAffinity)= -59 kJ/mole (energy is released Be: EA= approximately 0 B,C: EA= negative N: EA= positive F: EA= large, negative Magnetic Behavior: unpaired electrons Transition Metals: Ions of Metals Sc= 4s 3d 1 + 0 1 Sc = 4s 3d Fe= 4s 3d 6 3+ 0 5 Fe = 4s 3d Periodic Table: IE Radius IE Metallic Radius Intro to Chapter 10: Catenation of atoms: Linking of atoms of the same elements together Valence shell electrons: outer shell electrons Phosphorus: 3s 3p ==> 5 valence shell electrons 2 5 - F: 2s 2p ===> 7e linking 5 fluorine to 1 phosphorus to complete the fluorine electrons Chapter 10: Chemical Bonding G.N. Lewis=> valence shell electron interactions between atoms ---> Lewis Dot Structure electrons that are farthest away from nucleus are the ones that will play a part in bonding 1 Na: 3s 2 6 Cl: 3s 3p ==> Na : [Ne] - ==> Cl: [Ar] E system R (Na....Cl) C+H----> CH 4 H 2 2 - C: 2s 2p => 4e in valence shell H C H H: 1s1 (methane not ionic) H Pauling: how do we assess the degree of electron sharing (ionic or covalent) A+B---->A B + - ΔE 1 IP a EA b - + A+B---->AB ΔE 2 EA +aIP b For equal electron sharing, ΔE 1 ΔE 2 IPa+ EA b EA + aP b IPa- EA a IP b EA b Pauling: came up with electronegativity scale X Degree of ionic character in a bond Fr=4 X is proportioned toΔEN X *not including Noble Gases X EN X X EN X X Cs=0.8 X For NaCl---> EN: Na=0.9, Cl=3.0---> ΔE= 2.1---> ionic Lewis Structures: ==> Diatomic Elements: N , 2 ,2F ,2Cl 2 N: 5 valence shell electrons N=N Formal Charge on each element= ideal is for formal charge (FC) = 0 on each element FC= number of valence shell electrons- number of nonbonding electrons- (½)number of bonding pair electrons For N in N 2 5-2- (½)6= 0 For O in O 2 2 4 O: 2s 2p O=O FC on O= 6-4- (½)4= 0 For CO: 2 2 2 4 C: 2s 2p , O: 2s 2p :C=O: FC(C)= 4-2- (½)6= -1 FC(O)= 6-2- (½)6= +1 For NO: N: 2s 2p4 2 4 O: 2s 2p 11 valence shell electrons total N=O FC(N)=0 FC(O)=0 O has 8 electrons (full), N has 7 (incomplete) For CO2: 2 2 2 4 - C: 2s 2p , O: (2s 2p )2----> 16e C + O ------> O=C=O H O 2 H 2O 3 H 2O -3--> 2H + CO 3- 2- - CO 3 4+6(3)+2= 24e O FC=-1 O Resonance Structures FC=-1 C C O O O O FC=0