Nonbonding electrons, bond

The nonbonding electron clouds of the attached fluorine atoms tend to repel the oncoming fluorine molecules as they approach the carbon skeleton. This reduces the number of effective coUisions, making it possible to increase the total number of coUisions and stiU not accelerate the reaction rate as the reaction proceeds toward completion. This protective sheath of fluorine atoms provides the inertness of Teflon and other fluorocarbons. It also explains the fact that greater success in direct fluorination processes has been reported when the hydrocarbon to be fluorinated had already been partiaUy fluorinated by some other process or was prechlorinated, ie, the protective sheath of halogens reduced the number of reactive coUisions and aUowed reactions to occur without excessive cleavage of carbon—carbon bonds or mnaway exothermic processes. 

Heterocyclic cations in which the bonding number is increased by a process other than the addition of a proton (or equivalent) present a special situation. Structures of this type usually result from the participation of an originally nonbonding electron pair or a heteroatom in the formation of a ring or a multiple bond. 

The preferred conformation is D because it maximizes the number of antiperiplanar relationships between nonbonded electron pairs and C—O bonds while avoiding the R -R van der Waals repulsions in conformations E and F. 

Write line-bond structures for the following substances, showing all nonbonding electrons ... 

The same is true for the nitrogen atom in ammonia, which has three covalent N-H bonds and two nonbonding electrons (a lone pair). Atomic nitrogen has five valence electrons, and the ammonia nitrogen also has five—one in each of three shared N-H bonds plus two in the lone pair. Thus, the nitrogen atom in ammonia has no formal charge. 

Sulfur bonding electrons = 6 Sulfur nonbonding electrons = 2... 

Oxygen valence electrons = 6 Oxygen bonding electrons = 2 Oxygen nonbonding electrons = 6... 

Resonance forms differ only in the placement of their tt or nonbonding electrons. Neither the position nor the hybridization of any atom changes from one resonance form to another. In the acetate ion, for example, the carbon atom is sp2-hybridized and the oxygen atoms remain in exactly the same place in both resonance forms. Only the positions of the r electrons in the C=0 bond and the lone-pair electrons on oxygen differ from one form to another. This movement of electrons from one resonance structure to another can be indicated by using curved arrows. A curved arrow always indicates the movement of electrons, not the movement of atoms. An arrow shows that a pair of electrons moves from the atom or bond at the tail of the arrow to the atom or bond at the head of the arrow. 

The Lewis definition of a base as a compound with a pair of nonbonding electrons that it can use to bond to a Lewis acid is similar to the Bronsted-Lowry definition. Thus, H20, with its two pairs of nonbonding electrons on oxygen, acts as a Lewis base by donating an electron pair to an H+ in forming the hydronium ion, H30+. 

Some substances, such as acetate ion and benzene, can t be represented by a single line-bond structure and must be considered as a resonance hybrid of two or more structures, neither of which is correct by itself. The only difference between two resonance forms is in the location of their tt and nonbonding electrons. The nuclei remain in the same places in both structures, and the hybridization of the atoms remains the same. 

Nonbonding electrons (Section 1.4) Valence electrons that are not used in forming covalent bonds. 

In a molecule that has lone pairs or a single nonbonding electron on the central atom, the valence electrons contribute to the electron arrangement about the central atom but only bonded atoms are considered in the identification of the shape. Lone pairs distort the shape of a molecule so as to reduce lone pair-bonding pair repulsions. 

The N—>P dative bonds are weak and different in lengths (1.800 A on average), and the triflate anions are effectively extended to consider interaction with the counter ion. Again the phosphorus atom is strongly pyramidalized and features the aspects of an inert nonbonding electron pair. 

To summarize, the provisionai Lewis structure reached after Step 4 may not aiiocate an optimum number of eiectrons to one or more of the inner atoms. The eiectron distribution must be optimized when any inner atom does not have at ieast eight eiectrons or when an inner atom from beyond the second row has a positive formal charge. In either of these situations, a more stabie structure resuits from transferring nonbonding electrons from outer atoms to inner atoms to create doubie bonds (four shared electrons) or triple bonds (six shared electrons). 

When heated, azodicarbonamide breaks apart into gaseous carbon monoxide, nitrogen, and ammonia. Azodicarbonamide is used as a foaming agent in the polymer indushy. (a) Add nonbonding electron pairs and multiple bonds as required to complete the Lewis stmcture of this molecule, (b) Determine the geometry around each inner atom. 

The Lewis structure of hydrogen fluoride shows three lone pairs on the fluorine atom. These nonbonding electrons are localized in atomic orbitals that belong solely to fluorine. Remembering that one of the fluorine 2 p orbitals is used to form the H—F bond, we conclude that the three lone pairs must occupy the remaining pair 2 p orbitals and the 2 s orbital of the fluorine atom. 

---