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Resonance effect - when we can draw two (or more) forms of the same molecule that differ 

only in the placement of their electrons. Resonance usually reduces basicity. Why?

Resonancedelocalizeselectrondensityfromtheatomthatwantstoshareitselectrons,  which leadsto

thestructurebeingaweakerbasestrongercon!ugateacid.

"nducti#e $ffect: %heeffectonelectrondensityinoneportionofamoleculeduetoelectron

withdrawingorelectrondonatinggroupselsewhereinthemolecule.

Inductiveeffectdependsonthefollowing:

1. Electronegativityofthegroup Fluorinewithdrawsmoreelectrondensityfromneighboring

atomstowardsitselfthanHydrogenwould. =lowerbasicity(smaller pa!.

 ". #umberofelectronwithdrawingorelectrondonatinggroups $hegreaterthenumberof 

electronwithdrawinggroups%$hesmallerthenumberof electrondonating groups =lowerbasicity(smaller pa!.

&. 'istancefromthegroup $hesmallerthedistancefromtheelectronwithdrawinggroup%$he

greaterthedistancefromthe electrondonatinggroup =lowerbasicity(smaller pa!

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&ypercon!ugation - %his is #ery similar to resonance, sometimes referred to a 'o-bond

resonance or aker-'athan effect. "n case of classical resonance we had seen the

in#ol#ement of lone pair of electrons and pi bonds (doubletriple bonds). "n

hypercon!ugation single bonds are in#ol#ed in the electron delocalization circuitry. %his

effect is still not fully understood in detail but would ser#e the purpose of basic organic

chemistry.

teric effect - two or more groups or atoms come in close pro*imity to each other

(precisely within each other+s #an der Waals radii (definition of #an der Waals radii can

be found in any standard te*tbook)) and result in a mutual repulsion.

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&ydrogen bond - a weak type of force that forms a special type of dipole-dipole

attraction which occurs when a hydrogen atom bonded to a strongly electronegati#e

atom e*ists in the #icinity of another electronegati#e atom with a lone pair of electrons.

%hese bonds are generally stronger than ordinary dipole-dipole and dispersion forces,

but weaker than true co#alent and ionic bonds.