Lewis structures procedure followed

In writing Lewis structures, the following procedure is to be followed ... 

Table 14m this section sets forth the procedure to be followed m writ mg Lewis structures for organic molecules It begins with experimentally determined information the molecular formula and the constitution (order m which the atoms are connected)... 

The general procedure for constructing the Lewis structure of any molecule or ion is set out in Toolbox 2.1 at the end of this section, but the following information is essential for applying those rules. 

The strategy for a Lewis structure is always the same. Follow the six-step procedure. 

You can use the procedure outlined below to draw the Lewis structures for molecules and ions that have a central atom, with other atoms around it. The Sample Problems and additional text that follow show how to apply these steps for several molecules and polyatomic ions that obey the octet rule. Afterwards, use Practice Problems 9 to 13 to practice drawing Lewis structures. 

We will follow the usual procedure for obtaining the Lewis structure for the NO - ion. 

Drawing a Lewis structure for larger molecules is easier if you follow a stepwise procedure. 

Although it is fairly easy to draw Lewis structures for most compounds formed by nonmetals, it is a good idea to follow a regular procedure. The following steps should be used to determine Lewis structures. 

The shortcut described above works well for many simple uncharged molecules, but it does not work reliably for molecules that are more complex or for polyatomic ions. To draw Lewis structures for these, you can use the stepwise procedure described in the following sample study sheet. 

Shortcut The shortcut to drawing Lewis structures described in Section 3.3 can often be used for uncharged molecules such as CH3Br. Carbon atoms usually have four bonds and no lone pairs, hydrogen atoms always have one bond, and bromine atoms most commonly have one bond and three lone pairs. The only way to give these atoms their most common bonding patterns is with the following Lewis structure, which is the same Lewis structure we arrived at with the stepwise procedure. 

The following examples illustrate the four-step procedure for writing Lewis structures of compounds and an ion. 

The 3-step procedure given by (2- 2) on page 59 can also be applied for composite ions such as sulphate, nitrate, cyanide etc. We are going to look more into that in the following example where the Lewis structure for nitrate will be written down. During this procedure we will run into the concept of resonance structures. 

We will follow the usual procedure for obtaining the Lewis structure for the N02 ion. In NO2 there are 5 + 2(6) + 1 = 18 valence electrons. Indicating the single bonds gives the structure... 

Strategy We follow the procedure for diawing Lewis structures outlined in Section 9.6 of the text. After we complete the Lewis stnictm-e, we draw the resonance structures. 

Lewis structures can help us understand the bonding in many compounds and are frequently used when discussing the properties of molecules. For this reason, drawing Lewis structures is an important skill that you should practice. To do so, you should use the following procedure. 

A second type of exception occurs when there are fewer than eight valence electrons around an atom in a molecule or polyatomic ion. This situation is also relatively rare (with the exception of hydrogen and helium as we have aheady discussed), most often encountered in compounds of boron and beryllium. As an example, let s consider boron trifluoride, BF3. If we follow the first four steps of our procedure for drawing Lewis structures, we obtain the structure... 

Follow the same procedure as part (a) for parts (b), (c), and (d). Tlie appropriate Lewis structures are ... 

Analyze and Plan We are asked to draw a Lewis structure from a molecular formula. Our plan is to follow the five-step procedure just described. 

Solution We follow the procedure already outlined for writing Lewis structures. 

Soiution We follow the preceding procedure for writing Lewis structures and note that this is an anion with two negative charges. 

By comparing the number of electrons in an isolated atom with the number of electrons that are associated with the same atom in a Lewis structure, we can determine the distribution of electrons in the molecule and draw the most plausible Lewis structure. The bookkeeping procedure is as follows In an isolated atom, the number of electrons associated with the atom is simply the number of valence electrons. (As usual, we need not be concerned with the inner electrons.) In a molecule, electrons associated with the atom... 

We follow the procedure used for drawing Lewis structures and calculating formal charges in Examples 9.5 and 9.6. 

Strategy P is a third-period element, so it can have an expanded octeL if necessary. Follow the procedures given in Examples 3.4 and 3.5 to draw the Lewis structure and calculate formal charges. 

Strategy Follow the procedures in Examples 3.4 and 3.5 for drawing Lewis structures and calculating formal charges. Xe is a fifth-period element, so it may need to expand its octet to accommodate aU of the valence electrons. 

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