CHE 131 Lecture Notes - Lecture 34: Molecular Orbital Theory, Sigma Bond, Pi Bond

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viridianhare340

13 Nov 2018

School

Stony Brook University

Department

Chemistry

Course

CHE 131

Professor

Benjamin Hsiao

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CHE 131 Lecture Notes - Lecture 33: Valence Bond Theory, Sigma Bond, Covalent Bond

CHE 131 Lecture Notes - Lecture 34: Molecular Orbital Theory, Sigma Bond, Pi Bond

CHE 131 Lecture Notes - Lecture 35: Intermolecular Force, Atomic Orbital, Aufbau Principle

Document Summary

Che 131 lecture 34: hybridization and molecular orbital theory. Hybridization: unhybridized p orbitals can be used to form double bonds. In these double bonds, there can be pi bonds found: pi bonds have an electron density that lies above and below the plane of the nuclei. A double bond has a sigma and a pi bond. A triple bond has a sigma bond and 2 pi bonds: sigma bonds will always be used first. The sigma bonds form the skeletal structure of the molecule which is why they"re used up first. If there are resonance structures, the pi bond is delocalized. Molecular orbital theory: the atomic orbitals combine to produce a new set of bonding and anti-bonding molecular orbitals that exist between the nuclei. It goes from atomic orbitals to molecular orbitals. If the wave functions destructively interfere, they produce an anti bonding orbital.

Related Questions

For each of TWO molecules, methylamine and acrylonitrile , do the following:

1) Draw the lewis structure. Redraw (if needed) to show the correct bond angles.

2) Label every central atom with a molecular geometry and a hybridization.

3) Count up all pi bonds and all sigma bonds.

4) Draw the bonding orbitals of the sigma structure (flower pictures!). Annotate your bonds to indicate which orbitals are overlapping to produce bonds.

5) Draw the pi structure of your molecule. Annotate the drawing to indicate which orbitals are overlapping to form bonds.

yellowtrout509

Use valence bond theory to describe the bonding and geometry in theSeF4 molecule.

A. The central atom is Se, which has five electron groups around it(four bonding pairs and one nonbonding/lone pair). Theelectron-group geometry is trigonal bipyramidal (and the moleculargeometry is see-saw). To facilitate this geometry, the Se atom'sorbitals are hybridized as sp3d orbitals. Four of these hybridorbitals contain one of Se's 6 valence electrons each, and thesehybrid orbitals overlap with unhybridized p orbitals of the four Fatoms. The fifth hybrid orbital of Se contains a lone pair ofelectrons. There are 4 sigma bonds and 0 pi bonds in thismolecule.
B. The central atom is Se, which has six electron groups around it.The electron-group geometry is octahedral. To facilitate thisgeometry, the Se atom's orbitals are hybridized as sp3d2 orbitals.Four of these hybrid orbitals contain one of Se's 6 valenceelectrons each, and these hybrid orbitals overlap with unhybridizedp orbitals of the four F atoms. The fifth and sixth hybrid orbitalsof Se contain lone pairs of electrons. There are 4 sigma bonds and0 pi bonds in this molecule.
C. The central atom is Se, which has four electron groups aroundit. The electron-group geometry is tetrahedral. To facilitate thisgeometry, the Se atom's orbitals are hybridized as sp3 orbitals.These hybrid orbitals overlap with unhybridized p orbitals of thefour F atoms. There are 4 sigma bonds and 0 pi bonds in thismolecule.
D. The central atom is Se, which has four electron groups aroundit, two single bonds and two double bonds. The electron-groupgeometry is tetrahedral. To facilitate this geometry, the Se atom'sorbitals are hybridized as sp3 orbitals. These hybrid orbitalscontain one electron each of Se's 6 valence electrons, and thesehybrid orbitals overlap with unhybridized p orbitals of the four Fatoms. The final 2 electrons of Se's 6 valence electrons reside inunhybridized p orbitals, which overlap with unhybridized p orbitalsof the F atoms. There are 4 sigma bonds and 2 pi bonds in thismolecule.

CHE 131 Lecture Notes - Lecture 34: Molecular Orbital Theory, Sigma Bond, Pi Bond

CHE 131 Lecture Notes - Lecture 33: Valence Bond Theory, Sigma Bond, Covalent Bond

CHE 131 Lecture Notes - Lecture 34: Molecular Orbital Theory, Sigma Bond, Pi Bond

CHE 131 Lecture Notes - Lecture 35: Intermolecular Force, Atomic Orbital, Aufbau Principle

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