Lewis octet rule

Polar structures must be used for compounds containing an atom in a higher valence state, such as sulfur or phosphorus. Thus, if we treat sulfur in dimethyl sulfoxide (DMSO) formally as a divalent atom, the calculated index, 0, is compatible with the structure in Figure 1.12. We must use only formulas with filled valence shells that is, the Lewis octet rule must be obeyed. 

Eighteen-electron rule — An electron-counting rule to which an overwhelming majority of stable diamagnetic transition metal complexes adhere. The number of non-bonded electrons at the metal plus the number of electrons in the metal-ligand bonds should be 18. The 18-electron rule in transition metal chemistry is a full analogue of the Lewis octet rule . 

ZintI Phases. Invoking Lewis octet rule, Hume-Rothery published his 8 —N rule in 1930 to explain the crystal stmctures of the p-block elements (Hume-Rothery, 1930, 1931). In this expression, N stands for the number of valence electrons on the p-block atom. An atom with four or more valence electrons forms 8 - N bonds with its nearest neighbors, thus completing its octet. The Bavarian chemist Eduard Zintl (1898-1941) later extended Hume-Rothery s (8 - N) mle to ionic compounds (Zintl, 1939). In studying the stmcture of NaTl, Zintl noted that the Tl anion has four valence electrons and he, therefore, reasoned that this ion should bond to four neighboring ions. 

Summarize the essential features of the Lewis octet rule. The octet rule applies mainly to the second-period elements. Explain. 

Lewis octet rule. 298 Lifschitz salts, 308 Ligands, 300 UH2. 94 UH ,94... 

An explanation for this apparent violation of the octet rule is found in a more sophisticated description of atomic structure by quantum mechanics (Section 1-6). However, you will notice that, even in these cases, you can construct dipolar forms in which the Lewis octet rule is preserved (see Section 1-5). Indeed, structural and computational data show that these formulations contribnte strongly to the resonance picture of such molecules. 

For many years chemists used Lewis octet rule to explain the stability of molecules. However, this rule did not explain the stability of compounds such as PCI5 and SF4, both of which contain a central atom with 10 electrons formally associated with it. Throughout the years chemists explained the stability of such electron rich species by invoking the use of /-orbitals to accommodate the expansion of the valence octet resulting in sp d hybridization (7). However, subsequent studies (2-4) of such electron rich species showed inconsistencies in the electron distributions expected in sp d hybridization. 

A property of main group atoms which have the ability to acquire coordination numbers greater than 4 (which would comply with the Lewis octet rule). Hypercoordination may be associated with hypervalency, but usually is referred to peculiar atomic centers in electron-deficient species with multicenter cr-bonding, in which pairs of electrons are spread over more than two atoms. 

The ability of an atom in a molecular entity to expand its valence shell beyond the limits of the Lewis octet rule. Hyper-valent compounds are common for the second and subsequent row elements in groups 15 -18 of the periodic table. Hyperva-lent bonding implies a transfer of the electrons from the central (hypervalent) atom to the nonbonding molecular orbitals which it forms with (usually more electronegative) ligands. A typical example of a hypervalent bond is a linear three-center, four-electron bond, e.g., that of the Fap-P-Fap fragment of PF5. 

In 1916, the American chemist G. N. Lewis proposed that elements react to obtain the electron configurations of the inert gases. This hypothesis is summarized in the Lewis octet rule for second period atoms Atoms tend to combine and form bonds by transferring or sharing electrons until each atom contains eight electrons in its valence shell. Note that hydrogen requires only two electrons to complete its valence shell because it has only a Is orbital. 

Lewis octet rule A rule referring to the eight electrons in the valence sheU of an atom or ion in a... 

Lewis said that C, N, O, and F must have an octet. (He didn t know about carbocations.) The fact that third-row elements like sulfur and phosphorous can expand their octets is not a violation of Lewis octet rule. 

The bonding type realized in the latter case implies formation of familiar a-orbitals of the hypervalent (i.e., expanding its valence shell beyond the limits of the Lewis octet rule) T-shaped electron-rich center also bearing two lone pairs that can be presented as their symmetry-adapted MO equivalents. " The bi lone pair contributes to the formation of the aromatic decet of the bicyclic species lb, thus providing for the extra stability of its Czy structure. 

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