Hybrid Orbitals Rozhan Akhound-Sadegh Charlotte Anjun Hu Jessica Yihong Lu Jessica Review on VSEPR Theory Use the VSEPR model to predict the molecular geometry of (a) O3, (b) SnCl3.
a double bond counts as a single electron domain. Molecular Orbital Theory Valence bond and molecular orbital theories are used to explain chemical bonding. Molecular Orbital Theory (MO Theory): a molecule also has distinct energy levels like atoms have. Electrons rearranged around the molecules.
Valance Bond Theory Valence bond is also used to explain chemical bonding. Two atoms that have unpaired electrons in their orbitals which have opposite spins can overlap to give rise to a chemical bond. - MO and VB result in the same. - The paired electrons spread out to form the final electron clouds. Difference VB Theory: electrons of molecules move on the atomic orbitals. MO Theory: electrons move on the molecular orbitals. Molecular orbitals are made up by atomic
orbitals but not atomic orbitals. Now we know the theories that might help with predicting bonding behaviors BUT How exactly is it done? We know its not as simple as throwing basketball to a team member And we want to relate back to waveparticle duality weve covered in the
last unit... Charlotte Sigma bonds Along the internuclear axis
Increased electron probability density Between 2 nuclei Lobes of two orbitals overlap end to end Sigma bonds
?????? Example: Ethane C2H6 Pi bonds Parallel to the internuclear
axis BUT... Electron probability = 0 @ internuclear axis Electron probability divided into 2 regions. (2 chucks = 1 pi bond!) Increased electron probability
density above and below 2 nuclei Lobes of two orbitals overlap side to side (Dufferin-Peel Catholic District School Board, 2012) Example: Ethene C2H4
Sigma bonds Pi bonds Single and multiple bonds Multiple bonds only (forms only in addition to a sigma bond) head-on overlapping of atomic
orbitals Sideway overlapping Along the internuclear axis Parallel to the inter-nuclear axis Relatively shorter
Relatively longer Relatively stronger Relatively weaker Sigma bonds Pi bonds
Symmetrical asymmetrical Free rotation is possible Rotation will break the bond May exist on its own, may exist without p orbitals
Does not involve s orbitals but cant form without a sigma bond Only one lobe of the p-orbital is involved Both lobes of the p-orbital are involved
Larger overlap area Smaller overlap area Now we know the valence electron theory and the 2 types of bonds (read: constructive interference) BUT The valence electron theory
is FLAWED. For instance, carbon is predicted to have 2 bonds for overlapping while it actually has 4. How can we solve this? And how can we apply the knowledge of sigma/pi bonds to predict the actual 3d geometry of a more complex molecule? Rozhan
CH4 HYBRIDIZATION _ 1s
2s 2p 2 bonds?? 2 unpaired electrons 2 1s2 2
2sp 3 2 BeF2 i i i i i 2p
Energy 2s2 1s
2 i 2p Hybridize 2sp
1s2 Linear BF3 i i i Energy
2s2 1s 2
2p i i i 2p 2sp2
1s2 Hybridize Trigonal planar C 2H 4
_ 1s2 2s2 2p2 Hybridize
1s2 _ 2p1 C 2H 4
CO2 _ 1s2 2s2 2p2
Hybridize 1s2 2sp
2p2 Wrap-up (CrashCourse, 2013) Wrap-up Practice Kahoot
True or False Sigma bonds restricts rotation atoms around the bond axis. Formation of Pi bonds results in higher electron density above and below the bond axis. Each bond is associated with two overlapped orbitals Overlapping orbitals always have the same spin number ANS: F T F F
How many sigma and pi bonds are in there? 1. SO3 2. [SO3]23. [SO4]24. CH3COOH ANS: 1. 33 2. 31 3. 42 4. 71
Matching 1. Ethyne 2. Ethane 3. Ethene ANS: 1c 2a 3b What is the hybridization of an oxygen atom in a water molecule?
1. sp 2. sp2 3. sp3 ANS: sp3 Organic Challenge!(Khan Academy Organic Chemistry, 2014) Identify hybridization states and predict the geometries for all the atoms except hydrogen
Bibliography Yau. Chem 121. Retrieved October 20, 2016, from Community College of Baltimore County, http://faculty.ccbcmd.edu/~cyau/zzzzzz%20121%20YAU%20Sp%202015.htm Jespersen, N. D., Chemistry, , St John, & York, N. (2014). Barrons AP chemistry, 7th edition (7th ed.). Albany, NY, United States: Barrons Educational Series Inc.,U.S. Quantum Mechanics and Bonding Hybridization. (n.d.). Lecture. Retrieved October 20, 2016, from http://www.dpcdsb.org/NR/rdonlyres/9B6E4EF6-77F0-407F-A858-F0DF78B6896C/ 106061/46QuantumMechanicsandBondingHybridization.pdf Khan Academy Organic Chemistry (2014, May 17). Organic hybridization practice | chemical bonds | chemistry | khan academy Retrieved from https://youtu.be/GuaozMpFS3w
CrashCourse (2013, August 5). Orbitals: Crash course chemistry #25 Retrieved from https://youtu.be/cPDptc0wUYI Thanks! Rozhan Akhound-Sadegh Charlotte Anjun Hu Jessica Yihong Lu
