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1
Organic Chemistry
Introduction
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Atomic number :- number of proton inside nucleus or number of
electrons surrounding nucleus.
Mass number :- total number of protons and neutrons in an atomic
nucleus.
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4
Covalent Bonds
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Type of Hybridization
Number of sigma bond :
4 = SP3
3 = SP2
2 = SP
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Characterization of SP3 Hybridization
1- Shape :- Tetrahedral "Pyramidal"
2- Bond Angle :- 109.5o
3- Bond Length :- 1.5 Ao
4- S Character :- 25%
5- P Character :- 75%
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Characterization of SP2 Hybridization
1-Shape :- Trigonal "Planar "
2- Bond Angle :- 120o
3- Bond Length :- 1.3Ao
4- S Character :- 33.3 %
6- P Character :- 66.7 %
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Characterization of SP Hybridization
1- Shape :- Linear
2- Bond Angle :- 180o
3- Bond Length :- 1.2 Ao
4- S Character :- 50%
5- P Character :- 50%
We make a table for Hybridization types
Hybridization SP3
SP2
SP
Shape Tetrahedral
"Pyramidal"
Trigonal Linear
Bond Angle 109.5o 120
o 180
o
Bond Length 1.5Ao 1.3A
o 1.2A
o
Example Methane (CH4) Ethylene (C2H6) Acetylene (C2H2)
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Distinguish between sigma bond and pi bond
Sigma Bond(δ) Pi Bond(π)
Formed by linear overlap Formed by lateral overlap
Strong bond Weak bond
Formed in :-
1- 2- 2 Hybrid orbitals ex: ethane
3- Hybrid orbital + S ex: methane
Formed in :-
Not Hybrid orbitals
Has independent existence Has dependent existence
Free rotation Restricted rotation
Type of Hybridization
Number of "Sigma bonds + Ione pair of electrone
All halogens possess three lone pair
Ex1:- water molecule (H2O)
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Non – bonding orbital : Orbital contain lone pair of electrons.
Ex 2 :- ammonia molecule (NH3)
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Determine Type of Hybridization
Definitions
Organic Chemistry :- It is the chemistry of carbon and
hydrogen
Valence :- It is the number of electrons a needed to fill the
valence shell of atom.
Octet Rule :- The outer most shell ( valence shell) must be
filled with eight electrons.
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Hybridization :- It is the mixing of orbitals in valence shell to
form hybrid orbitals have identical shape and same bond angle
and same energy.
Atoms have lone pair of electrons :
1- Hetero atoms
2- Halogens
F , Cl , Br , I = have three lone pair
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Hybridization of ions
Carbcation C+
Carboanion C-
Free radical C.
Types of fission "Cleavage"
Heterolytic Fission
From carbocation C+ and Carboanion C
-
Homolytic Fission
From carbo Radical C.
Hybridization of ions
Carbcation C+ No Hybridization
Carboanion C- yes Hybridization
Free radical C. No Hybridization
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Negative charge Calculate in hybridization except in states the
following :-
Atom that contain one lone pair of electron or negative charge
and all bond its single and connected with atom it has
hybridization SP2 or SP will no calculated lone pair of electron
and no negative charge.
Atom that contain two lone pair of electrons and all bond its single
and connected with atom it has hybridization SP2 or SP will
calculated only one lone pair of electron.
Atom that contain one or two lone pair of electrons but from
double bond . calculate all lone pair of electrons.
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Inductive – mesomeric effect
mesomeric effect
Complete transfer of electrons through Pi bond " double , triple bond"
Bond order :- Is the number of chemical bonds between a pair of atom.
As the bond order increase the bond will stronger and shorter
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Valence and bonding in organic compounds
Table : Valence of common elements
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Polarity of Bonds :- depends on the electronegativity difference of the
atoms formic this bond .
Table :- Electronegativity of some common elements
I II III IV V VI VII
H Be B C N O F
Li Mg Al Si P S Cl
Na Ca Br
K I
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Arrows
Straight arrow
Pair of straight arrow with half head
Is used to indicate the equilibrium reaction
Double headed straight arrow
Is used to indicate the Resonance
Curved arrow
Is used to indicate the movement a pair from electrons
Fish hock arrow
Is used to indicate the movement one from electrons