Sigma and Pi Bonding SWBAT: Draw Quantum Mechanical models of molecules using sigma and pi bonding
Feb 23, 2016
Sigma and Pi BondingSWBAT: Draw Quantum Mechanical models of molecules using sigma and pi bonding
Carbon HybridizationType of hybrid
Atomic orbitals
used
Number of hybrid orbitals formed
Number of atoms
bonded to the C
Aufbau Chart
sp3 s, p, p, p 4 4
sp2 s, p, p 3 3
sp s, p 2 2
Carbon HybridizationType of hybrid
Atomic orbitals
used
Number of hybrid orbitals formed
Number of atoms
bonded to the C
Aufbau Chart
sp3 s, p, p, p 4 4
sp2 s, p, p 3 3
sp s, p 2 2
sp3 Hybridization
Carbon HybridizationType of hybrid
Atomic orbitals
used
Number of hybrid orbitals formed
Number of atoms
bonded to the C
Aufbau Chart
sp3 s, p, p, p 4 4
sp2 s, p, p 3 3
sp s, p 2 2
sp2 Hybridization C2H4
Carbon HybridizationType of hybrid
Atomic orbitals
used
Number of hybrid orbitals formed
Number of atoms
bonded to the C
Aufbau Chart
sp3 s, p, p, p 4 4
sp2 s, p, p 3 3
sp s, p 2 2
sp Hybridization C2H2
Covalent Bonds The formation of a covalent bond involves
the overlapping of half filled atomic orbitals
The two different categories of covalent bonds are Sigma and Pi covalent bonds
Sigma bonding Bond is formed by the axial overlapping
of half filled atomic orbitals The electron cloud formed is
cylindrically symmetrical about inter nuclear axis
The electrons constituting sigma bonds are called sigma electrons
3 Types of Sigma Bonding1. s-s overlap2. s-p overlap3. p-p overlap
sp-overlaps Example: CH4
Strength of Sigma Bonds The strength of three types of sigma
bonds varies as follows p-p > p-s > s-s A p-p overlap is greater than an s-s
overlap allowing it to be stronger
Pi Bonding This type of covalent bond is formed by the
lateral or sidewise overlap of the atomic orbitals
The orbital overlap takes place in a way that their axes are parallel to each other but perpendicular to the internuclear axis
The pi bond consists of two charge clouds above and below the plane of the atoms involved in the bond formation
The electrons involved in the p bond formation are called pi electrons
Pi Bonding
Sigma and Pi Bonding
Sigma bonds are stronger than pi bonds (greater overlap between orbitals occurs)
Pi bonding between the two atoms is formed only in addition to a sigma bond (Sigma first then Pi)
Atoms rotate around sigma bonds but not pi bonds
The shape of the molecule is controlled by the orientations of sigma bonds around the central atom. Pi bonds are superimposed on sigma bonds.
Sigma and Pi bonding with Oxygen (O2) 1s22s22p4
s orbitals are filled and the 2px orbital is filled
The 2py and 2pz orbitals are partially filled An O=O molecule has one sigma and one
pi bond (connect both lobes of a p orbital for a pi bond…. Draw two lines for one pi bond)
Oxygen (O2) Nitrogen (N2)
Carbon Hybridization Review http://www.chemit.co.uk/resource/downl
oad/94