Anion Lewis structure

All the following compounds are charactenzed by ionic bonding between a group I metal cation and a tetrahedral anion Wnte an appropriate Lewis structure for each anion remembenng to specify formal charges where they exist... 

Although Lewis structures of this type are not entirely adequate descriptions of the structure of the excited states, they do correspond to the MO picture by indicating distortion of chaige and the presence of polar or radical-like centers. The excited states are much more reactive than the corresponding ground-state molecules. In addition to the increased energy content, this high reactivity is associated with the presence of half-filled orbitals. The two SOMO orbitals in the excited states have enhanced radical, cationic, or anionic character. 

Draw Lewis structures for methyl anion, ammonia and hydronium cation. How many electrons are left over in each after all bonds have been made Display and compare electron density surfaces for methyl anion, ammonia and hydronium cation. Which is the smallest molecule Which is the largest Rationalize your observation. (Hint Compare the number of electrons in each molecule, and the nuclear charge on the central atom in each molecule.)... 

Nucleophiles can also act as acids and bases, and this behavior substantially alters their nucleophilicity. At pH 5, trimethylamine exists mainly as its conjugate acid, trimethylammonium cation. First draw a Lewis structure, and then examine the electrostatic potential for trimethylammonium ion. On the basis of the map, which is the better nucleophile, the cation or the corresponding neutral amine At pH 12, phenol exists mainly as its conjugate base, phenoxide anion. First draw a Lewis structure (or series of Lewis structures), and then examine the electrostatic potential map for phenoxide anion. Which is the better nucleophile, phenoxide or phenol ... 

Phenol has different chemical properties from those of typical alcohols. Display the electrostatic potential map for phenol. Does this suggest that phenol is likely to be a stronger or weaker acid than any of the compounds discussed above Compare the electrostatic potential map for 4-nitrophenol to that for phenol. What effect does substitution by nitro have on acid strength Explain your result by considering charge delocalization in the conjugate base. Draw all reasonable Lewis structures for phenoxide anion and for 4-nitrophenoxide anion. Which is more delocalized Is this consistent with experimental pKa s ... 

How many different enolates may arise from deprotonation of 2,4-pentanedione Draw Lewis structures for each, and predict which is likely to be the most stable. Check your conclusions by examining the energies of the different possible enolates (enolate A, B...). Is the most stable enolate that derived from deprotonation of the most electron-poor hydrogen Compare the electrostatic potential maps of the anions with each other and with your Lewis structures. Revise your drawings to be consistent with the maps. Why is one of the enolates preferred over the others ... 

Draw Lewis stmctures for the anion resulting from addition of methoxide to fluorobenzene. Is the negative charge highly localized or is it delocalized over several positions Examine calculated charges for the anion. Are they in accord with those anticipated from the Lewis structures ... 

Some ligands have more than one atom with an unshared pair of electrons and hence can form more than one bond with a central metal atom. Ligands of this type are referred to as chelating agents the complexes formed are referred to as chelates (from the Greek chela, crab s claw). Two of the most common chelating agents are the oxalate anion (abbreviated ox) and the ethylenediamine molecule (abbreviated en), whose Lewis structures are... 

Quinone, C6H4On is an organic molecule with the structure shown below it can be reduced to the anion C(iI l4Or. (a) Draw the Lewis structure of the reduced product, (b) On the basis of formal charges derived from the Lewis structure, predict which atoms in the molecule are most negatively charged, (c) If two protons are added to the reduced product, where are they most likely to bond ... 

The reaction between SbF and CsF produces, among other products, the anion [Sb2F7]. This anion has no F—F bonds and no Sb—Sb bonds, (a) Propose a Lewis structure for the ion. (b) Assign a hybridization scheme to the Sb atoms. 

A Lewis structure shows all valence electrons and only valence electrons, so a correct count of valence electrons is essential. Recall from Section 8- that the number of valence electrons of an atom can be found from its position in the periodic table. Add the contributions from all atoms to obtain a total count of valence electrons. If the species is an anion, add one electron for each negative charge if the species is a cation, subtract one electron for each positive charge. 

Which of these options is the best Lewis structure Actually, no single Lewis structure by itself is an accurate representation of NO3. Any single structure of the anion shows nitrate with one NDO double bond and two N— O single bonds. In Section 9 1, we show that single and double bonds between the same types of atoms have different lengths and different energies. In contrast, experiments show that the three nitrate N—O bonds are identical. To show that the nitrate N—O bonds are all alike, we use a composite of the three equivalent Lewis structures. These are traditionally called resonance structures. Resonance stmctures are connected by double-headed arrows to emphasize that a complete depiction requires all of them. 

It is essential to realize that electrons In the nitrate anion do not flip back and forth among the three bonds, as implied by separate structures. The true character of the anion is a blend of the three, In which all three nitrogen-oxygen bonds are equivalent. The need to show several equivalent structures for such species reflects the fact that Lewis structures are approximate representations. They reveal much about how electrons are distributed in a molecule or ion, but they are imperfect instruments that cannot describe the entire story of chemical bonding, hi Chapter 10, we show how to interpret these structures from a more detailed bonding perspective. 

C09-0025. Describe the geometry and draw a ball-and-stick sketch of gallium triiodide. C09-0026. Describe the geometry and draw a ball-and-stick sketch of the ASCI4 anion. C09-0027. Determine the Lewis structure and describe the geometry of XeOF4. ... 

The acetate anion has 24 valence electrons, leading to a Lewis structure with two resonance forms ... 

In addition to four atoms in a row, a four-atom deiocaiized framework can have a centrai atom surrounded by three other atoms with which it interacts. An exampie is the carbonate anion, whose Lewis structure dispiays resonance ... 

Several elements in row 3 of the periodic table form itt bonds to oxygen through side-by-side overlap of 3 cf and 2 p orbitals. An example is the sulfate anion, whose Lewis structure appears in Figure 10-48. The steric number... 

Hg (CN0)2, which explodes when struck. Write a Lewis structure for the CNO anion and describe its bonding, including any delocalized orbitals. 

C21-0053. Three phosphate anions can condense to form a ring whose chemical formula Is P3 Og. Determine the Lewis structure and draw a ball-and-stick model of this anion. 

There are also molecules that are exceptions to the octet rule because one of the atoms has fewer, rather than more than, eight electrons in its valence shell in the Lewis structure (Figure 1.19). These molecules are formed by the elements on the left-hand side of the periodic table that have only one, two, or three electrons in their valence shells and cannot therefore attain an octet by using each of their electrons to form a covalent bond. The molecules LiF, BeCl2, BF3, and AIC13 would be examples. However, as we have seen and as we will discuss in detail in Chapters 8 and 9, these molecules are predominately ionic. In terms of a fully ionic model, each atom has a completed shell, and the anions obey the octet rule. Only if they are regarded as covalent can they be considered to be exceptions to the octet rule. Covalent descriptions of the bonding in BF3 and related molecules have therefore... 

The term metalla-/3-diketonate refers to an anionic diacyl complex, such as L M(RCO)(R CO) , in which the two acyl ligands occupy adjacent coordination sites of the metal atom. Resonance stabilization of the negative charge by 7r-delocalization onto the two acyl ligands gives Lewis structures 1 and 2. The two acyl ligands acquire an acyl/carbene... 

A The Lewis structure for the cation, the anion, and the compound follows the explanation. 

B Below each explanation are the Lewis structures for the cation, for the anion, and for the compound. 

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