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Water is the^ medium^ for^ life
Life evolved^ in^ water^ due^ to^ the^ protection^ it^ provides^ from
g.
UV light; Organisms typically contain^70 -^90 % Water;
chemical reactions^ occur^ in^ aqueous environments^ ; Water is a critical determinant^ of^ the^ structure^ and^ function^ of Proteins,nucleic acids^ , and^ membrane The (^) octect rule dictates^ that^ there^ are^4 electron pairs around^ an^ oxygen atom^ in^ water^ ~
*É÷%:÷÷☒¥ *
. B@ These electrons are^ in^ four^ Sp
(^) orbitals Two of these (^) pairs (^) covalently link two^ hydrogen (^) •^ •
atoms to^ a central oxygen atom
- • g- g- The two (^) remaining pairs are^ nonbonding (lone^ pairs)^ 8- water (^) geometry is^ a^ distorted
- (^) A (^) tetrahedron / Dipole Moment
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The (^) electronegativity a-+ne^ oxygen atom induces^ a^ net^ dipole^ moment Because (^) of the (^) dipole moment,water can^ serve as both^ a (^) hydrogen bond^ donor^ and^ acceptor
Hydrogen Bonds R
1 Hydrogen bonds are strong dipole - dipole
1 Or^ charge -^ dipole^ interactions^ that^ arise [ strong hydrogen
~ bond^ between^ a^ covalently bound^ hydrogen and^ lone pair of^ electrons p 1 Typically involve (^2) electronegative % ^ Weaker atoms^ ;frequently^ nitrogen^ and (^) oxygen p
hydrogen bond Hydrogen bonds (^) are (^) strongest when^ the bonded molecules^ allow for^ linear 3 atoms involved (^) are (^) bonding patterns EE•÷••:•.¥• in a^ line k⑨qg%a B-ioBIFH.as.IM#I*qi-iEBEM water can serve^ as an H^ donor^ and ④⑧%•¥•q;É¥¥
an H^ acceptor
§q•i¥§•?% " *÷←¥É•••%¥a÷ Hydrogen bonding^ in^ water •_•^ :•μ is (^) cooperative (^) up to 4 H- (^) bonds (^) per water molecule give water^ its cooperative effect^
Increases donor^ strength^ High boiling^ point;^ high^ melting
of (^) a (^) hydrogen-bond^ If^ it point and^ Large surface concurrently acts^ as^
an tension
acceptor for^ a^ 2nd^ hydrogen^ H-bonds between (^) neighboring molecules bond (^) are weak C.20k) 1m01) relative to^ the^ H
- O covalent bonds^ (^420 Kj^ 1m01^ )
