Electronegativity is the attraction that an atom has for a pair of electrons it is sharing with anot

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Electronegativity is the attraction that an atom
has for a pair of electrons it is sharing with
another atom.
This attraction results from the positively
charged core of the atom and increases with this
charge.
When two atoms with different electronegativities
are bonded, a bond dipole results.
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Dipoles may also result from formal charges
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Resonance
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Compare allyl carbocation with allene
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RULES OF RESONANCE
1) Individual resonance forms are imaginary, not
real
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2) Resonance forms differ only in the placement
of their ? and nonbonding electrons.
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3) Different resonance forms of a substance dont
have to be equivalent.
In these instances the real species (resonance
hybrid) looks more like the lower energy
resonance structure.
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4) Resonance forms must be valid resonance
structures and obey normal rules of valency.
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5) The resonance hybrid is more stable than any
individual resonance form.
What experimental evidence is there that the
hybrid (real) molecule is lower in energy than
the resonance structures?
It is the form that actually exists
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ACID-BASE CHEMISTRY
Lowry-Bronstead
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The larger the value of Ka the stronger the acid.
pKa - log Ka (smaller pKa stronger acid)
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Problems 2.11 2.14
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Predicting acid strength based on structure
       Electronegativity In general, a
hydrogen atom that is bonded to a more
electronegative atom is more acidic.
Arrange the following in order of acidity
Rank the Hs in this molecule in order of acidity
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Anion Size Neutral acids that form larger
conjugate bases are more acidic.
Arrange the following in order of acidity
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Lewis Acid Base Theory Curved arrows
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Drawing Chemical Formulas (Representing molecules)
Molecular formulas
C2H2Cl2
Kekule or Lewis structures
Condensed structures
CHClCHCl
Skeletal structures (lines / rings)
3-D structures
Molecular models
Computer modeling (electrostatic map) Page 61