F' J' Grieman

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F. J. Grieman
Chemical Bonding (1) Atom Review Lowest energy
from multiple interaction Ionic bond Covalent
bond Polar covalent Ionic character Electronegati
vity and type of bond Bonding Model Requirements
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Atomic Structure Review
electron interference ?
H.U.P Quantized Energy ?
Orbitals
Multielectron Atom
3 interactions
Energy f(? Q.s)
Pauli and Hund ?
Periodic Table
3
Molecules
Model
Molecules properties can be very different than
atoms
How?
Interactions
Why do systems seek lowest energy?
Lowest energy is our guide
Understand from thermodynamics

• ball on hill

Energy released to surroundings
Organized energy
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Molecule
A B ? AB ? AB energy
(organized) ? Equilibrium
Possible ways to form molecules
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ionic combine IE, EA, Coulombic
Attraction energy Na(g) ?
Cl(g) e-
? ------------------------------------------------
----------------------------------- Na(g)
Cl(g) ? E
Na(g) Cl-(g) ? Coulombic
Attraction E (2.31 x 10-19 Jnm/molecule)

(1.39 x 102 kJnm/mol) Q1Q2/r(nm) r(Na)
r(Cl-) .095 .181 .276 nm (solid)
r .251 nm
(gas) E(Coulomb) BE(NaCl)
kJ/mol Graph on overhead

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Cl2 ?? Cl energy ? Cl e- Cl
e- ? Cl- energy --------------------
--------------------------------------- Cl Cl
?
!!!!!! Coulombic Energy r(Cl2) must But r(Cl-)
Cl would have to be inside Cl- !!!!! Must
be something else
electron sharing somehow Must let
be our guide right now (Overhead and
demonstration)
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hetero molecules somewhere between covalent
and ionic ?
? Polar?? From dipole (two poles)
Dipole moment
amount of charge separated by distance R Measure
in Debye 3.336E-30Cm
Measure of extent of Calculate ?( ) for
complete charge transfer e.g., NaCl-
x 100 NaCl ?(calc)
( C)(2.51E-10m)/3.336E-30D/Cm)
12.0 D Ionic Character
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• (Cl2) 0 further evidence that covalent
• Ionic gt
• Electronegativity
• The greater ?EN, the more ionic
• Molecule Cl-Cl HCl NaCl
• EN
• ?EN
• Polar covalent example
• H?Cl ?(actual)
  r(HCl)
• ?(calc)

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• Bonding Model should explain and/or predict