Bond Formation and Hybrid Orbitals

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Bond Formation and Hybrid Orbitals Textbook
Reference pp.400 - 410
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Hybrid Orbitals
We consider the energy of the s an p blocks to be
close enough that rather than consider an s
sub-shell and a p sub-shell, containing 2 and 6
electrons, respectively we treat them all as the
same energy level. This notion allows us to
rationalize the ease with which carbon can form 4
bonds, nitrogen forms 3 bonds and a lone pair (or
4 bonds)
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Formation of Hybrid Orbitals
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Types of Hybrid Orbitals
When we have an atom with 4 available spaces (a
central atom with 4 atoms bonded to it) we need
to use the s and all 3 p orbitals to form the
hybrid orbitals which we designate sp3.
If our central atom is 3 coordinate (therefore
tigonal planar) we say its hybridization is sp2.
If our central atom is in a a linear arrangement
(2 coordinate) its hybridization is said to be sp.
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Bond Formation and Type
We know that atoms use their valence electrons to
form covalent bonds. We also know that there can
be multiple covalent bonds between two atoms
(NO3-, C2H2). If we consider two covalent bonds
will repel one another (e- - e- repulsion) how do
we fit 3 bonds between the 2 carbon atoms in
acetylene (aka ethyne aka C2H2)?
There are two types of covalent bond - s
(sigma) bonds - p (pi) bonds Single bonds
contain only a s bond while double bonds contain
a s and a p bond and a triple bond is made up of
a s and two p bonds.
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s bonds, p bonds . . . What the . . . ?
To form a s bond a hybrid orbital (sp, sp2 or
sp3) must interact with that of a terminal atom
(group). A p bond is the result of the leftover
or un-hybridized orbitals on the central
atom. Consider H-CC-H - both carbons are sp
hybridized (1 s bond to H 1 s bond to the other
C) - the two remaining p orbitals on each carbon
are said to overlap and each form another
covalent bond
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Some more examples of hybrid orbitals