Oxygen octet rule followed

The octet rule accounts for the valences of many of the elements and the structures of many compounds. Carbon, nitrogen, oxygen, and fluorine obey the octet rule rigorously, provided there are enough electrons to go around. However, some compounds have an odd number of electrons. In addition, an atom of phosphorus, sulfur, chlorine, or another nonmetal in Period 3 and subsequent periods can accommodate more than eight electrons in its valence shell. The following two sections show how to recognize exceptions to the octet rule. 

The structures that are shown here are those in which the central atom makes use of the four orbitals corresponding to a noble-gas structure. There is evidence, however, that the central atom deviates from the octet rule, making use of additional orbitals and the unshared pairs of the oxygen atoms to form bonds with considerable double-bond character. Thus perchloric acid might be shown with the following structure, in which the chlorine atom forms double bonds with three oxygen atoms and a single bond with the fourth ... 

Simple molecules such as water follow the octet rule, in which eight electrons surround the oxygen atom. The hydrogen atoms share two electrons each with the oxygen, forming the familiar picture with two bonds and two lone pairs ... 

Write Lewis structures that obey the octet rule (duet rule for H) for each of the following molecules. Carbon Is the central atom In CH4, nitrogen Is the central atom In NH3, and oxygen Is the... 

The compounds containing the elements carbon, nitrogen, oxygen, and fluorine are accurately described by Lewis structures in the vast majority of cases. However, there are a few exceptions. One important example is the oxygen molecule, O2. The following Lewis structure that satisfies the octet rule can be drawn for O2 (see Self-Check Exercise 12.4). 

The sum of the shared (bonding) electrons and the lone pair electrons for carbon, nitrogen, oxygen, and fluorine atoms must be eight—an octet. Usually the other elements in groups IV, V, VI, and VII also follow the octet rule. 

For each of the following molecules or ions of sulfur and oxygen, write a single Lewis structure that obeys the octet rule, and calculate the oxidation numbers and formal charges on all the atoms (a) SO2, (b) SO3, (c) 803 . (d) Arrange these mol-ecules/ions in order of increasing S — O bond distance. 

SCHEME 6.3 Molecules that contain either a single oxygen or a single sulfur atom and as many fluorine atoms as needed. The molecules following the octet rule are highlighted in yellow, and the electron-rich ones are highlighted in orange. 

Ozone is one of those odd molecules that negotiate with the octet rule. Its electronic structure can be written following the rule as two structures, which are depicted in the bottom part of Scheme 10.R. 1, with a double-headed arrow between them. Recall that the double-headed arrow means that the two structures contribute equally to the description of the molecule, which has thereby four mobile electrons (recall benzene in Scheme 4.R.3). It turns out, however, that quantum mechanics (QM) calculations predict that these two descriptions are minor, and the major description of ozone is the structure that is seen in the scheme to possess two regular 0—0 bonds and one long bond between the two terminal oxygen atoms. The bond lengths of the molecule show that this is not a short bond like the other two. 1 have put the reference of a scientific book, not as an actual source of reading material, but rather just to show you that this electronic structure is discussed somewhere in these terms. 

Electron delocalization in the acyl cation derived from propanoyl chloride is represented by the following two resonance contributors. Note that electron release from oxygen generates a contributing structure that satishes the octet rule and disperses the posihve charge. 

The most common errors in Lewis diagrams are bonding oxygen atoms to each other and surrounding a central atom with three or five electron pairs. There are some compounds in which oxygen atoms are bonded to each other, but not many. One of these appears in the question section that follows. The three- or five-electron pair errors most often occur when double bonds are present. Always check your final diagram to be sure all atoms conform to the octet rule. 

The number of covalent bonds formed by an atom is termed its COVALENCY. The covalency of an atom is equal to the number of electrons the atom needs to become isoelectronic with a noble gas. Some of the more common elements have the following covalencies when they follow the octet rule and also have no charge hydrogen and the halogens, 1 oxygen and sulfur, 2 nitrogen and phosphorus, 3 carbon and silicon, 4. LEWIS ELECTRONIC FORMULAS, in which bonds and unshared electrons are shown, are given for a few typical compounds of these elements ... 

The octet rule must be followed. That is, no second-row atom can he left with ten electrons (or four for hydrogen). If an electron pair moves to an atom that already has an octet (or two for hydrogen), another electron pair must simultaneously move from that atom to maintain the octet. When two electrons move from the C=C bond of ethylene to the hydrogen atom of HsO" ", for instance, two electrons must leave that hydrogen. This means that the H-0 bond must break and the electrons must stay with the oxygen, giving neutral water. 

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