CHEM 14A Chapter Notes - Chapter 2F.4: Ethane, Sigma Bond, Orbital Hybridisation

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turquoisemoose666

6 Dec 2020

School

UCLA

Department

Chemistry and Biochemistry

Course

CHEM 14A

Professor

Dr.Laurence Lavelle

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Document Summary

Each of the three hybrid orbitals on the c atom has one electron available for bonding. The fourth valence e- of each c atom occupies the unhybridized 2p-orbital. Two carbon atoms form a sigma bond by overlap of an sp2 hybrid orbital on each atom. H atoms for sigma bonds with the remaining lobes. The electrons in the two unhybridized 2p-orbitals form a pi bond through side by side overlap. The presence of carbon=carbon strongly influences the shape of a molecule. Prevents one part from rotating relative to another part. Two 2p-orbitals overlap best if all six atoms of the two ch2 groups lie in the same plane. Double bonds are important for living organisms. Depends on the shape of the molecule retinal in the retina of the eye. Cis-retinal is held rigid by its double bonds. When light enters the eye, it excites an electron out of the -bond. Carbon-carbon triple bond < three carbon-carbon single bonds.

Related Questions

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.

Benzene is an organic chemical compound with the molecular formula C6H6. In the benzene molecule, carbon atoms form a ring with alternating single and double bonds connecting them. Thus, each individual carbon atom forms one ? bond with another carbon atom and one ? and one ? bond with another carbon atom. Each carbon atom also forms one ? bond with a hydrogen atom. Identify which types of orbitals overlap to form the bonds between the atoms in a benzene molecule. Drag the appropriate labels to their respective targets.

Attached is picture. Please explain/show work, will give 5 stars to correct answer, thank you very much! :)

Chemical bonds are formed by linear combinations of atomic orbital's. These atomic orbital's should have compatible energies. An axial overlap of these orbitals results in the formation of a sigma bond, whereas a lateral overlap results in the formation of a pi bond. When two atomic orbitai's on different atoms approach each other, two molecular orbital's are formed: one bonding molecular orbital and one antibonding molecular orbital. The bonding molecular orbital has a lower energy than the corresponding atomic orbital's: antibonding orbital's have higher energies than the corresponding atomic orbital's. An example using the hydrogen molecule is shown here. However, the same rule applies to systems with multiple atomic orbital's. For each atomic orbital that overlaps, one molecular orbital must form. In the diagram below. 1s orbitais from two hydrogen atoms combine to form one bonding sigma1 orbital and one antibonding orbital. The total number of bonding and antibonding orbital's is always equal to the number of orbital's that overlap. Similarly, molecular orbital's can also be formed by the overlapping of hybrid orbital's. The hybrid orbital's are formed by the linear combination of different atomic orbital's of nearly equal energy on the same atom. The atomic orbital's of nearly equal energy undergo a process of mixing and reorientation to form new orbital's of lower energy. This process is called hybridization For example, hybridization of one s and two p orbital's on an atom forms three sp2 hybrid orbital's. Benzene is an organic chemical compound with the molecular formula C6H6. In the benzene molecule, carbon atoms form a ring with alternating single and double bonds connecting them. Thus, each individual carbon atom forms one sigma bond with another carbon atom and one sigma and one pi bond with another carbon atom. Each carbon atom also forms one sigma bond with a hydrogen atom. Identify which types of orbital's overlap to form the bonds between the atoms in a benzene molecule.

Answer True or false for the following questions.

1) There are eleven Ï bonds in this molecule?

2) There are three lone pairs of electrons in the complete Lewisstructure?

3) The C-N bond is formed from overlap of an sp3 hybrid orbitalfrom the carbon atom with an sp2 hybrid orbital from the nitrogenatom?

4) An sp2 hybrid orbital on C-1 overlaps with an sp3 hybrid orbitalon C-2 to form the sigma bond between C-1 and C-2?

5) There are four Ï bonds in this molecule?

6)The C-2 and C-3 atoms cannot rotate about the internuclear axisbetween the two atoms since the Ï bond would break?

7) The Ï bond between C-3 and O is formed by overlap ofunhybridized p atomic orbitals?

CHEM 14A Chapter Notes - Chapter 2F.4: Ethane, Sigma Bond, Orbital Hybridisation

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