Writing Lewis symbols

Give the name and formula of an ionic compound involving only the elements in each pair that follows. Write Lewis symbols for the elements both before and after chemical combination. 

Write Lewis symbols (using dots or crosses) for the following neutral atoms. The number of electrons In each atom Is shown In brackets ... 

Write Lewis symbols for atoms and ions. (Section 8.1)... 

Electron spin had not yet been proposed when Lewis framed his theory, and so he did not show that two of the valence electrons (3s ) are paired and two (3p ) are unpaired. We will write Lewis symbols in the way Lewis did. We will place single dots on the sides of the symbol, up to a maximum of four. Then we will pair up dots until we reach an octet. Lewis symbols are commonly written for main-group elements but much less often for transition elements. Lewis symbols for several main-group elements are written in Example 10-1. 

Lewis, G. N., 60, 64, 398 Lewis acid, 398, 473, 671 Lewis base, 398, 473 Lewis structure, 65 writing, 67 Lewis symbol, 60 Lewis theory, limitations of, 115... 

Lewis recognized that certain molecules such a PCI5 and SF6 are exceptions to the octet rule because their Lewis structures indicate that the central atom has more than eight electrons in its valence shell 10 for the P atom in PCI5 and the S atom in SF4, and 12 for the S atom in SFg (Figure 1.17). Such molecules are called hypervalent because the valence of the central atom is greater than its principal valence. To write a Lewis structure for such molecules, the Lewis symbol for the hypervalent atom must be modified to show the correct number of unpaired electrons. For the molecules in Figure 1.17 we would need to write the Lewis symbols as follows ... 

Using Lewis symbols, write a balanced chemical equation showing the formation of lithium fluoride, LiF, from isolated lithium and fluorine atoms. 

To work out the formula of an ionic compound using Lewis symbols, we first represent the cation by removing the dots from the symbol for the metal atom. Then we represent the anion by transferring those dots to the Lewis symbol for the nonmetal atom to complete its valence shell. We may need to adjust the numbers of atoms of each kind so that all the dots removed from the metal atom symbols are accommodated by the nonmetal atom symbols. Finally, we write the charge of each ion as a superscript in the normal way. A simple example is the formula of potassium chloride ... 

The simplest organic molecule is the hydrocarbon methane, CH4. To write its Lewis structure, we count the valence electrons available from all the atoms in the molecule. For methane, the Lewis symbols of the atoms are... 

Writing electron configurations to illustrate what happens to the electrons in bonding is an unwieldy process. Because it is the valence electrons that participate in an atom s reactions, a symbol can be used that includes only these electrons. G. N. Lewis, a noted chemist in the early 1900s, devised such a system. In order to write the Lewis symbol for any element, follow these steps. 

Write the Lewis symbol for each of the following elements. 

Observe that the sodium loses one electron and the chlorine gains one electron. This one-to-one ratio is not always the case. Suppose that the reaction under consideration is between magnesium and chlorine. Writing the Lewis symbols for each shows that magnesium has two valence electrons to give away, whereas chlorine has a vacancy for only one. Therefore, another chlorine atom is needed to provide a place for the second available magnesium electron. This is described in Lewis symbols as... 

Use Lewis symbols to show the transfer of electrons in each of the following combinations. This will allow you to see how many atoms of each element must be present so that you can then write the correct formula for the compound. 

Write the electron configuration for each halogen atom. Write the Lewis symbol for a halogen atom, X. What is... 

Write the Lewis symbols for potassium, oxygen, silicon, and chlorine. 

Write the Lewis symbols for carbon, magnesium, chlorine, and arsenic. 

Using Lewis symbols for each element, write the equations to show the transfer of electrons and the formation of ions for the following ionic compounds (a) Na20 and (b) A1C13. 

Using Lewis symbols, write an equation predicting the product of the reaction of ... 

It s easy to write the Lewis symbol for any main-group element ... 

Magnesium reacts with fluorine to form magnesium fluoride. Write an equation to describe the bonding using Lewis symbols. 

The bonding in the compound can be shown by writing an equation using Lewis symbols, as follows ... 

Write equations for the formation of the following compounds, using Lewis symbols. Use Table 3.3 for electronic arrangements ... 

Write the symbols for the atoms, show which atoms are attached to which, and connect them with a single hond (a dash, representing two electrons). Chemical formulas are often written in the order in which the atoms are connected in the molecule or ion. The formula HCN, for example, tells you that the carbon atom is bonded to the H and to the N. In many polyatomic molecules and ions, the central atom is usually written first, as in C03 and SF4. Remember that the central atom is generally less electronegative than the atoms surrounding it. In other cases, you may need more information before you can draw the Lewis structure. 

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