CHEM 322aL Chapter Notes - Chapter 1: Ethylene, Acetylene, Antibonding Molecular Orbital

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11 Sep 2017

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Chapter i: remembering general chemistry: electronic structure and bonding. How the electrons in an atom are distributed. Atomic orbitals (s, p, d, f) have characteristic shapes and energies, they also occupy a characteristic volume of space. Degenerate orbitals have the same amount of energy. The aufbau principle states that an e- always goes into the available orbital with the lowest energy. The pauli exclusion principle states that no more than two e- can occupy each atomic orbital and they must have opposite spin. Hund"s rule states that when there are 2+ atomic orbitals with the same energy an e- will occupy an empty orbital before it will pair up with another e- The octet rule states that atoms are the most stable if the outer shell are filled or contains 8 e- How the structure of a compounded is represented. A radical (free radical) is an atom with a single unpaired e: atomic orbitals.

Related Questions

Atomic and molecular orbitals

a) What do graphical representations of orbitals typically show? How is this related to the statements often found in general chemistry textbooks about a large fraction of the electron density being enclosed in some three-dimensional surfaces ?

b) For many-electron atoms and molecules, why do we describe the electronic structure in terms of orbitals. Shouldnât we just solve the SchrÃ¶dinger equation and use the many-electron wavefunction instead?

c) In the context of orbital theory as taught in this course, what does âorbital occupationâ really mean?

d) State the Pauli principle in its most general form, and its consequences in molecular orbital theory.

e) Is there a unique set of molecular orbitals for a given molecule? Give a reason for your answer, not just Yes or No.

f) Describe an electronic configuration that cannot be correctly described with a single Slater-determinant wavefunction

g) In molecular orbital calculations based on the self-consistent field (SCF) concept, how are the orbital energies and the total energy related?

h) Describe an example for an unintuitive outcome when you change the occupation numbers of the orbitals of a system.

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.

CHEM 322aL Chapter Notes - Chapter 1: Ethylene, Acetylene, Antibonding Molecular Orbital

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