hydrogen bond by a.sarkar
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P o n d i c h e r r y U n i v e r s i t y
Assignment on
HYDROGEN BONDINGSubmitted by
Angshuman Sarkar 11305006
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OVERVIEW• What is Chemical Bonding?
• Types of Bonding.
•
What is Hydrogen Bond?• How they are formed?
• Conditions of forming Hydrogen Bonding.
•
Types of Hydrogen Bond.• Properties of Hydrogen Bond.
• Effect of Hydrogen Bond.
•
Importance of Hydrogen Bond.
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WHAT IS CHEMICAL
BONDING?
The attractive forcewhich holds various
constituents(atoms,ions,etc) together
in different chemical
species is called a
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TYPES OF BONDING
1. Ionic bonds
2. Covalent bonds
3. Metallic bonds
4. Hydrogen bond
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IONIC COVALENT METALLIC
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Hydrogen bond
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DEFINATION OFHydrogen BondingIn chemistry, a hydrogen bond is a type of attractive intermolecular force that existsbetween two partial electric charges of
opposite polarity. Although stronger thanmost other intermolecular forces, thehydrogen bond is much weaker than both theionic bond and the covalent bond.
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In other words,Hydrogen bond is the attractiveforce which binds hydrogen atom of one
molecule with the electronegative atom(F,O,N)of other molecule.
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How They are formed
a hydrogen bond isformed when a chargedpart of a molecule havingpolar covalent bondsforms an electrostatic(charge, as in positiveattracted to negative)
interaction with asubstance of oppositecharge. Molecules thathave nonpolar
covalent bonds donot
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CONDITION FOR FORMATION
OF H-BONDØ Molecules must have a polar covalent bond.
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Ø
Hydrogen atom should be bonded toa highly electronegative atom suchas F, O or N.
Ø The size of electronegative atom
should be small.
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TYPES OF HYDROGEN
BONDSØ Intermolecular hydrogen bond
Ø Intramolecular hydrogen bond
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InterMolecular
hydrogen bondIt is formed between two different molecules.
Eg;- H-bond in water molecule,HF molecule.
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Intramolecule
hydrogen bondØ It is formed whenhydrogen atom is inbetween the two
highlyelectronegative(F,O,N)atoms present withinthe same molecule.
Eg;- o-nitrophenol,o-chlorophenol,salicylaldehyde
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Properties of h-bond
Hydrogen bond is a bond of hydrogenbetween two electronegative atoms only. Itnever involves more than two atoms.
Hydrogen bonds are classified as weak bonds because they are easily and rapidly formedand broken under normal biologicalconditions.
In the formation of hydrogen bond electronpair is not shared. In this respect it isdifferent from the covalent bond.
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The strength of hydrogen bond dependsupon the electronegativity of the atom A towhich hydrogen atom is attached with a
covalent bond
Typical hydrogen bond is linear.
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Effect of Hydrogen Bonding on
Physical Properties of theMolecules
Physical
StatesHydrogen bonding also influences thephysical state of the substances (solid,liquid or gas).
HydrogenBond inSolid(Ice)
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BOILING POINT
Hydrogen bond has a significant influence on amolecule's boiling points.
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MELTING POINT
Melting point for compounds of approximatelythe same molecular weight
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SOLUBILITY
Covalent compounds do not generally dissolvein water, but those that can form a hydrogenbond with water, readily dissolve in it.eg;-
Ammonia.
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IMPORTANCE OF H-
BONDING Thier presence explains many of the propertiesof the molecules.eg:- water.
They are used to stabilize and determine thestructure of large macormolecules like proteinsand nucleic acids.
protein folding.
They are involved in the mechanism of enzymecatalysis.
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ON-GOING WORK
highly cooperative hydrogen bonding in largewater clusters (n ≤ 24)
applicability of continuum methods in highlycooperative systems
non-classical hydrogen bonding in clathrates
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~:THANK YOU:~