Bonds Lewis symbols

Lewis symbols are named after G. N. Lewis (1875-1946), an American chemist who contributed greatly to our understanding of chemical bonding. Lewis symbols, or electron-dot symbols, show the number of valence electrons possessed by an element. They are used only for the main-group elements. Here is how Lewis symbols are written ... 

Chemical Bonding Lewis Symbols Principal Types of... 

We begin with descriptions of the three main types of chemical bonds ionic, covalent, and metallic. In evaluating bonding, Lewis symbols provide a useful shorthand for keeping track of valence electrons. 

CHEMICAL BONDS, LEWIS SYMBOLS, AND THE OCTET RULE (INTRODUCTION AND SECTION 8.1) In this chapter we have focused on the interactions that lead to the formation of chemical bonds. We classify these bonds into three broad groups ionic bonds, which result from the electrostatic forces that exist between ions of opposite charge covalent bonds, which result from the sharing of electrons by two atoms and metallic bonds, which result from a delocalized sharing of electrons in metals. The formation of bonds involves interactions of the outermost electrons of atoms, their valence electrons. The valence electrons of an atom can be represented by electron-dot symbols, called Lewis symbols. The tendencies of atoms to gain, lose, or share their valence electrons often follow the octet rule, which says that the atoms in molecules or ions (usually) have eight valence electrons. 

Chemical Bonds, Lewis Symbols, and the Octet Rule... 

Three Types of Bonding Lewis Symbols and the Octet Rule The Ionic Bonding Model... 

Ionic Bonding Lewis Symbols and Lattice Energies 384... 

As will become apparent as this chapter progresses, many of our basic ideas on the chemical bond were proposed by Ci. N. Lewis, one of the greatest of all chemists, in the early years of the twentieth century. Lewis devised a simple way to keep track of valence electrons when atoms form ionic bonds. He represented each valence electron as a dot and arranged the dots around the symbol of the element. A single dot represents an electron alone in an orbital a pair of dots represents two paired electrons sharing an orbital. Examples of the Lewis symbols of atoms are... 

We can extend the Lewis symbols introduced in Section 2.2 to describe covalent bonding by using a line (—) to represent a shared pair of electrons. For example, the hydrogen molecule formed when two H- atoms share an electron pair (H=H) is represented by the symbol H—H. A fluorine atom has seven valence electrons and needs one more to complete its octet. It can achieve an octet by accepting a share in an electron supplied by another atom, such as another fluorine atom ... 

A biradical is a molecule with two unpaired electrons. The unpaired electrons are usually on different atoms, as depicted in (20). In that biradical, one unpaired electron is on one carbon atom of the chain and the second is on another carbon atom several bonds away. In some cases, though, both electrons are on the same atom. One of the most important examples is the oxygen atom itself. Its electron configuration is He]2s22/ x.22py12pzl and its Lewis symbol is -O. The O atom has two unpaired electrons, and so it can be regarded as a special type of biradical. 

Bond structure can also be represented by lines. Each electron pair is shown by a line. In other words two electrons are shown by a line So the line representation of the fluorine molecule is IF—FI. The line between the two fluorine atoms represents the bond. Sometimes both the Lewis symbol and line representation can be used in the same molecule. For example, the F2 molecule can also be represented as F— F ... 

In Sections 9-3 and 9-4, we will show you two types of chemical bonds ionic and covalent. It is important to be able to represent compounds in terms of the atoms and valence electrons that make up the chemical species (compounds or polyatomic ions). One of the best ways is to use Lewis symbols and structures. 

The Lewis symbols will be used in the discussion of bonding, especially covalent bonding, and will form the basis of the discussion of molecular geometry. 

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. 

In ionic bonding, atoms gain and lose electrons in order to achieve a noble gas electron configuration. Here s how Lewis symbols show this electron gain and loss in the ionic bonding of sodium chloride ... 

Electrophile (Section 2.8) An electron-deficient compound, often symbolized by E, which can accept a pair of electrons from an electron-rich compound, forming a covalent bond. Lewis acids are electrophiles. 

It will require one sulfur atom to accept the two electrons lost by one magnesium atom. The formula of magnesium sulfide must be MgS. Again, Lewis symbols will be used to show the electron transfer from magnesium to sulfur. As with all ionic compounds, the ions in the crystal of MgS are held together by ionic bonds, the natural attraction between ions of opposite charge. 

Lewis structure. A representation of covalent bonding using Lewis symbols. Shared electron pairs are shown either as lines or as pairs of dots between two atoms, and lone pairs are shown as pairs of dots on individual atoms. (9.4) Ligand. A molecule or an ion that is bonded to the metal ion in a complex ion. (22.3) Limiting reagent. The reactant used up first in a reaction. (3.9)... 

Lewis Symbols Principal Types of Chemical Bonds Ionic and Covalent Polar Covalent Bonding and Electronegativity... 

The Lewis symbol, or Lewis structure, developed by G. N. Lewis early in this century, is a convenient way of representing atoms singly or in combination. Its principal advantage is that only valence electrons (those that may participate in bonding) are shown. 

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