Chemical 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... 

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... 

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. 

Electron-dot symbols for the first eighteen elements. This scheme, invented in the early twentieth century by G. N. Lewis, provides a rough but useful tool for predicting the availability of an atom s valence electrons for chemical bonding. 

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... 

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. 

In the nineteenth century the valence bond was represented by a line drawn between the symbols of two chemical elements, which expressed in a concise way many chemical facts, but which had only qualitative significance with regard to molecular structure. The nature of the bond was completely unknown. After the discovery of the electron numerous attempts were made to develop an electronic theory of the chemical bond. These culminated in the work of Lewis, who in... 

Electrons in the outermost occupied shell of any atom may play a significant role in that atoms chemical properties, including its ability to form chemical bonds. To indicate their importance, these electrons are called valence electrons (from the Latin valentia, strength ), and the shell they occupy is called the valence shell. Valence electrons can be conveniently represented as a series of dots surrounding an atomic symbol. This notation is called an electron-dot structure or, sometimes, a Lewis dot symbol, in honor of the American chemist G. N. Lewis, who first proposed the concepts of shells and valence electrons. Figure 6.2 shows the electron-dot structures for the atoms important in our discussions of ionic and covalent bonds. (Atoms of elements in groups 3 through 12 form metallic bonds, which we ll study in Chapter 18.)... 

Lewis Structures Lewis structures are one of the most useful and versatile tools in the chemist s toolbox. G. N. Lewis reported this model for chemical bonding in 1902. Lewis structures are nonmathematical models that allow us to qualitatively describe the chemical bonding in a molecule and then gain insights about the physical and chemical properties we can expect of that molecule. Don t discount the power of Lewis structures just because the underlying mathematics isn t evident. In a Lewis structure, the atoms are represented by their chemical symbol. Lines between atoms represents shared pairs of electrons in covalent bonds. Valence electrons that are not used for covalent bonds are lone pairs, and they are represented as pairs of dots on the atom. 

Electron-dot structures Because valence electrons are involved in forming chemical bonds, chemists often represent them visually using a simple shorthand method. An atom s electron-dot structure consists of the element s symbol, which represents the atomic nucleus and inner-level electrons, surrounded by dots representing the atom s valence electrons. The American chemist G. N. Lewis (1875-1946), devised the method while teaching a college chemistry class in 1902. 

The American chemist G. N. Lewis introduced a useful model that describes the electronic structure of the atom and provides a starting point for describing chemical bonds. The Lewis model represents the valence electrons as dots arranged around the chemical symbol for the atom the core electrons are not shown. The first four dots are displayed singly around the four sides of the elemental symbol. If the atom has more than four valence electrons, their dots are then paired with those already present. The result is a Lewis dot symbol for that atom. The Lewis notation for the elements of the first two periods is... 

Chemical bonding usually involves only the outermost electrons of atoms, also called valence electrons. In Lewis dot representations, only the electrons in the outermost occupied r and p orbitals are shown as dots. Paired and unpaired electrons are also indicated. Table 7-1 shows Lewis dot formulas for the representative elements. All elements in a given group have the same outer-shell electron configuration. It is somewhat arbitrary on which side of the atom symbol we write the electron dots. We do, however, represent an electron pair as a pair of dots and an unpaired electron as a single dot. 

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

Lewis Electron-Dot Symbols Depicting Atoms in Chemical Bonding... 

Now, if you were a benchwarmer like me, there was never a symbol on the board for you only the players who actually play in the game earn one of coach s Xs. The same is true when drawing electrons on a Lewis structures Only the electrons that can participate in chemical bonding, the valence electrons, earn a spot on the Lewis structure drawings. The electrons that are in the inner shells of an atom don t play a role in bonding, so they are ignored. 

The electrons involved in chemical bonding are the valence electrons, which, for most atoms, are tho.se in the outermost occupied shell. (Section 6.8) The American chemist G. N. Lewis (1875-1946) suggested a simple way of showing the valence electrons in an atom and tracking them during bond formation, using what are now known as either Lewis electron-dot symbols or simply Lewis symbols. 

The preceding discussion implicitly assumed the simple view of chemical bonding developed by G. N. Lewis. Atoms are represented by element symbols with dots around them to indicate the number of electrons in the valence shell of the atom. Covalent bonds are formed by the sharing of one or more pairs of electrons between atoms so that both atoms achieve an electron configuration corresponding to a filled outer shell. For example, combination of two chlorine atoms can produce a chlorine molecule, as shown in Figure 1.5. 

Lewis dot symbols of atoms help explain the valence of elements. The orignal definition of valence was derived from the number of chemical bonds that an element would form. Counting unpaired electrons In the Lewis symbol provides the valence of elements in the s and p blocks of the periodic table. 

Figure 7.6 I The Lewis symbols for elements in the first three periods of the periodic table are shown. Notice the similarities among elements in the same group. Lewis structures help keep track of electrons involved in chemical bonds.

Our study of chemical bonds begins with an introduction to Lewis dot symbols, which shows the valence electrons on an atom. (9.1)... 

The valence electrons in the outermost energy level of an atom are responsible for the electron activity that occurs to form chemical bonds. The Lewis structure of an atom is a representation that shows the valence electrons for that atom. American chemist Gilbert N. Lewis (1875-1946) proposed using the symbol for the element and dots for electrons. The number of dots placed around the symbol equals the number of s and p electrons in the outermost energy level of the atom. Paired dots represent paired electrons unpaired dots represent unpaired electrons. For example, H" is the Lewis symbol for a hydrogen atom, Is B is the Lewis symbol for a boron atom, with valence electrons 2s 2p In the case of boron, the symbol B represents the boron nucleus and the Is electrons the dots represent only the 2s 2p electrons. 

It is useful to have some simple way of showing the hydrogen atom s single electron in chemical symbols and formulas. This is accomplished with electron-dot symbols or Lewis symbols (after G. N. Lewis), which use dots around the symbol of an element to show outer electrons (those that may become involved in chemical bonds). The Lewis symbol for hydrogen is... 

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