MBB 222 Lecture Notes - Lecture 3: Aromaticity, Atomic Orbital, Aliphatic Compound

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browncricket987

20 Dec 2018

School

Simon Fraser University

Department

Molec Biol & Biochem

Course

MBB 222

Professor

Adam Barlev

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Document Summary

An important class of compounds in chemistry and biology is the aromatic compounds. These cyclic ring-shaped molecules have alternating single and double bonds, resulting in delocalization of their electrons to form a (pi) electron cloud. Compare benzene, an aromatic molecule, with cyclohexane, an aliphatic molecule. Cyclohexane: cyclized 6-carbon ring with carbons linked by single bonds. Benzene: cyclized 6-carbon ring with carbons linked by alternating single and double bonds. Each c has one h rigid, planar structure. Aromatic compound - electrons are delocalized in a cloud - resonance . Has unique properties due to resonance very stable (not reactive) Each electron is shared by all six carbons - the electrons are delocalized. While many compounds have bonds and exhibit resonance, only cyclic molecules that form a closed loop of overlapping orbitals are aromatic. Aromatic compounds usually have distinctive physical properties that affect their interactions with each other and with other molecules.

Related Questions

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.

For each of the following, fill in the blank with the correct response. All of these fill-in-the-blank problems pertain to material covered in the sections on alkanes, alkenes and alkynes, aromatic hydrocarbons, and hydrocarbon derivatives.

a. The first "organic" compound to be synthesized in the laboratory, rather than being isolated from nature, was _ _ _ _ _, which was prepared from _ _ _ _ _.

b. An organic compound whose carbon-carbon bonds are all single bonds is said to be _ _ _ _ _.

c. The general orientation of the four pairs of electrons around the carbon atoms in alkanes is _ _ _ _ _.

d. Alkanes in which the carbon atoms form a single unbranched chain are said to be _ _ _ _ _ alkanes.

e. Structural isomerism occurs when two molecules have the same number of each type of atom but exhibit a different arrangement of the _ _ _ _ _ between those atoms.

f. The systematic names of all saturated hydrocarbons have the ending _ _ _ _ _ added to a root name that indicates the number of carbon atoms in the molecule.

g. For branched hydrocarbon, the root name for the hydrocarbon comes from the number of carbon atoms in the _ _ _ _ _ continuous chain in the molecule.

h. The positions of substituents along the hydrocarbon framework of a molecule are indicated by the _ _ _ _ _ of the carbon atom to which the substituents are attached.

i. The major use of alkanes has been in _ _ _ _ _ reactions, as a source of heat and light.

j. With very reactive agents, such as the halogen elements, alkanes undergo _ _ _ _ _ reactions, whereby a new atom replaces one or more hydrogen atoms of the alkane.

k. Alkenes and alkynes are characterized by their ability to undergo rapid, complete _ _ _ _ _ reactions, by which other atoms attach themselves to the carbon atoms of the double or triple bond.

l. Unsaturated fats may be converted to saturated fats by the process of _ _ _ _ _.

m. Benzene is the parent member of the group of hydrocarbons called _ _ _ _ _ hydrocarbons.

n. An atom or group of atoms that imparts new and characteristic properties to an organic molecule is called a _ _ _ _ _ group.

o. A _ _ _ _ _ alcohol is one in which there is only one hydrocarbon group attached to the carbon atom holding the hydroxyl group.

p. The simplest alcohol, methanol, prepared industrially by the hydrogenation of _ _ _ _ _.

q. Ethanol is commonly prepared by the _ _ _ _ _ of certain sugars by yeast.

r. Both aldehydes and ketones contain the _ _ _ _ _ group, but they differ in where this group occurs along the hydrocarbon chain.

s. Aldehydes and ketones can be prepared by _ _ _ _ _ of the corresponding alcohol.

t. Organic acids, which contain the _ _ _ _ _ group, are typically weak acids.

u. The typical sweet-smelling compounds called _ _ _ _ _ result from the condensation reaction of organic acid with an _ _ _ _ _.

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MBB 222 Lecture Notes - Lecture 3: Aromaticity, Atomic Orbital, Aliphatic Compound

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