Slide 1: HYBRIDIZATION sp3 Slide 3: METHANE
WATER Slide 4: Quantum mechanics: describes electron energies
and locations by a wave equation
Wave function are solutions of wave equation
Each Wave function is an orbital , y
A plot of y 2 describes where electron most likely to be
Electron cloud has no specific boundary so we show most
probable area ORBITAL Slide 5: There is no way of determining the exact location of an
electron within an atom.
There is a definite 3 dimensional area around the nucleus
within which an electron is most likely to be found. ORBITAL Slide 6: SHAPE OF ORBITALS Slide 7: P-ORBITALS In each shell there are three
mutually perpendicular p
orbitals, px.py and pz of
equal energy The lobes of a p orbital are
separated by a region of zero
electron density ,a node Slide 8: Covalent bond forms when two atoms approach each other closely so that a singly occupied orbital on one atom overlaps a singly occupied orbital on the other atom There are two ways orbitals can overlap to form bonds
between atoms. BOND FORMATION Slide 9: Sigma () Bonds –Formed by s-s ,s-p and axial overlap of p-p orbitals Sigma bonds are characterized by Head-to-head overlap.
Cylindrical symmetry of electron density about the internuclear axis. s BOND Slide 10: Pi bonds are characterized by Side-to-side or lateral, or unsymmetrical overlap of atomic orbitals
Electron density above and below the internuclear axis. () Pi () Bonds Slide 11: bond formation Overlapping of atomic orbitals s and p bond formation Slide 12: Hybridization – mixing of two or more atomic
orbitals to form a new set of hybrid orbitals Number of hybrid orbitals is equal to number of pure atomic orbitals used in the hybridizationprocess. Mix at least 2 nonequivalent atomic orbitals (e.g. sand p).Hybrid orbitals have very different shapefrom original atomic orbitals. Hybridization Orbital Changes- Excitation : Orbital Changes- Excitation Slide 15: BONDING IN METHANE Sp3
HYBRIDIZATION ground state excited state hybridized state CARBON The formation of four sp3 hybrid orbitals by combination of an atomic s orbital with three atomic p orbitals. Each sp3 hybrid orbital has two lobes, one of which is larger than the other. The four large lobes are oriented toward the corners of a tetrahedron at angles of 109.5°. The carbon atom is sp3 hybridized to obtain tetrahedral geometry Slide 17: 17 s + 3 p 4 sp3 orbitals Slide 18: sp3 hybridized orbital
4 orbitals All the same shape, size and energy
Arranged in a tetrahedral conformation
Gives minimum repulsion between orbitals.
Angle of 109º from each other
Can form bonds by overlapping with orbitals of other
atoms. Slide 19: The bonding in methane. Each of the four C-H bonds results from head-on (s) overlap of a singly occupied carbon sp3 hybrid orbital with a singly occupied hydrogen 1s orbital. Sigma bonds are formed by head-to-head overlap between the hydrogen s orbital and a singly occupied sp3 hybrid orbital of carbon. BONDING IN METHANE Slide 20: In Ethane the two carbon atoms are in the Sp3 hybridized state Out of four Sp3-hybrid orbitals one Sp3-hybrid orbital of one C-atom overlaps with one s-orbital of H-atom to produce three sigma bond and the last overlaps with one Sp3-orbital of other C-atom axially to produce a sigma bond between two C-atoms. C2H6 CH3CH3 STRUCTURE OF ETHANE Slide 21: BONDING IN
ETHANE Slide 22: BONDING IN
AMMONIA In the case of ammonia, the three 2p orbitals of the nitrogen atom are combined with one 2s orbital to form four sp3 hybrid orbitals. The non-bonded electron pair will occupy a hybrid orbital.. Slide 23: The bonding geometry will not be tetrahedral when the valence shell of the central atom contains nonbonding electrons, however. The reason is that the nonbonding electrons are also in orbitals that occupy space and repel the other orbitals. This means that in figuring the coordination number around the central atom, we must count both the bonded atoms and the nonbonding pairs. BONDING IN
AMMONIA Slide 24: Ammonia assumes a pyramidal shape. More precisely, the shape is that of a trigonal pyramid (i.e., a pyramid having a triangular base). The fourth orbital containing the non-bonding electrons pushes the bonding orbitals together slightly, making the H–N–H bond angles about 107°. BONDING IN
AMMONIA Slide 25: BONDING IN
AMMONIUM ION The hybridization of N in Ammonium ion is sp3.In the formation of Ammonium ion the four hybrid orbitals contain bond pair therefore the shape is here also tetrahedral Slide 26: BONDING IN
WATER Two of the coordination positions are occupied by the shared electron-pairs that constitute the O–H bonds, and the other two by the non-bonding pairs. Thus although the oxygen atom is tetrahedrally coordinated, the bonding geometry (shape) of the H2O molecule is described as bent Slide 27: Thus in H2O, the two nonbonding orbitals push the bonding orbitals closer together, making the H–O–H angle 104.5° instead of the tetrahedral angle of 109.5°.