Covalent Lewis Structures Electrons Shared

Recall from Chapter 5 that when nonmetals bond with other nonmetals, a molecular compoimd results. Molecular compounds contain covalent bonds in which electrons are shared between atoms rather than transferred. In Lewis theory, we represent covalent bonding by allowing neighboring atoms to share some of their valence electrons in order to attain octets (or duets for hydrogen). For example, hydrogen and oxygen have the Lewis structures  

In water, hydrogen and oxygen share their electrons so that each hydrogen atom gets a duet and the oxygen atom gets an octet. 

I Remember that each dash represents a pair of shared electrons. 

The shared electrons—those that appear in the space between the two atoms— count toward the octets (or duets) of both of the atoms. 

Electrons that are shared between two atoms are called bonding pair electrons, while those that are only on one atom are called lone pair (or nonbonding) electrons. 

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Bonding Models and AIDS Drugs 325 10.4 Covalent Lewis Structures Electrons Shared 328 10.7... 

In some molecules and polyatomic ions, both electrons to be shared come from the same atom. The covalent bond formed is known as a coordinate or dative covalent bond. In Lewis structures (electron dot diagrams), a coordinate or dative bond is often denoted by an arrow pointing from the atom which donates the lone pair to the atom which receives it. 

In a covalent Lewis structure, neighboring atoms share valence electrons to attain octets (or duets). 

Formal charges are based on Lewis structures m which electrons are considered to be shared equally between covalently bonded atoms Actually polarization of N—H bonds m ammonium ion and of B—H bonds m borohydride leads to some transfer of positive and negative charge respectively to the hydrogens... 

Section 1 3 The most common kind of bonding involving carbon is covalent bond ing A covalent bond is the sharing of a pair of electrons between two atoms Lewis structures are written on the basis of the octet rule, which limits second row elements to no more than eight electrons m their valence shells In most of its compounds carbon has four bonds... 

Each atom in a polyatomic molecule completes its octet (or duplet for hydrogen) by sharing pairs of electrons with its immediate neighbors. Each shared pair counts as one covalent bond and is represented by a line between the two atoms. A Lewis structure does not portray the shape of a polyatomic molecule it simply displays which atoms are bonded together and which atoms have lone pairs. 

The structures used to show the bonding in covalent molecules are called Lewis structures. When bonding, atoms tend to achieve a noble gas configuration. By sharing electrons, individual atoms can complete the outer energy level. In a covalent bond, an octet of electrons is formed around each atom (except hydrogen.)... 

Lewis considered covalent and ionic bonds to be two extremes of the same general type of bond in which an electron pair is shared between two atoms contributing to the valence shell of both the bonded atoms. In other words, in writing his structures Lewis took no account of the polarity of bonds. As we will see much of the subsequent controversy concerning hypervalent molecules has arisen because of attempts to describe polar bonds in terms of Lewis structures. 

Figure 2.11 Lewis structure of the covalent hydrogen molecule in X Electrons which electrons are shared...

In general, first bond the multicovalent atoms to each other and then, to achieve their normal covalences, bond them to the univalent atoms (H, Cl, Br, I, and F). If the number of univalent atoms is insufficient for this purpose, use multiple bonds or form rings. In their bonded state, the second-period elements (C, N, O, and F) should have eight (an octet) electrons but not more. Furthermore, the number of electrons shown in the Lewis structure should equal the sum of all the valence electrons of the individual atoms in the molecule. Each bond represents a shared pair of electrons. 

Lewis structures provide information about what atoms are bonded to each other, and the total electron parrs involved. According to the Lewis theory, an atom will give up, accept or share electrons in order to achieve a filled outer shell that contains eight electrons. The Lewis structure of a covalent molecule shows all the electrons in the valence shell of each atom the bonds between atoms are shown as shared pairs of electrons. Atoms are most... 

In writing the conventional Lewis structures for molecules, we assume that a covalent chemical bond between two atoms involves sharing of a pair of electrons, one from each atom. Figure 6-5 shows how atomic orbitals can be considered to be used in bond formation. Here, we postulate that a single bond is formed by the pulling together of two atomic nuclei by attractive forces exerted by the nuclei for the two paired electrons in overlapping atomic orbitals. 

The familiar Lewis structure is the simplest bonding model in common use in organic chemistry. It is based on the idea that, at the simplest level, the ionic bonding force arises from the electrostatic attraction between ions of opposite charge, and the covalent bonding force arises from sharing of electron pairs between atoms. 

One of the most convenient ways to picture the sharing of electrons between atoms in covalent or polar covalent bonds is to use electron-dot structures, or Lewis structures, named after G. N. Lewis of the University of California at Berkeley. An electron-dot structure represents an atom s valence electrons by dots and indicates by the placement of the dots how the valence electrons are distributed in a molecule. A hydrogen molecule, for example, is written showing a pair of dots between the hydrogen atoms, indicating that the hydrogens share the pair of electrons in a covalent bond ... 

Almost simultaneous with the publication of Kossel s paper there appeared a rival electronic theory. The American chemist Lewis introduced the idea of the covalent electron-pair bond. Like Kossel, he was impressed by the apparent stability of the noble gas configuration. He was also impressed by the fact that, apart from many compounds of the transition elements, most compounds when rendered as molecules have even numbers of electrons, suggesting that electrons are usually found in pairs. Lewis devised the familiar representations of molecules and polyatomic ions (Lewis structures, or Lewis diagrams) in which electrons are shown as dots (or as noughts and crosses) to show how atoms can attain noble gas configurations by the sharing of electrons in pairs, as opposed to complete transfer as in Kossel s theory. It was soon apparent from the earliest X-ray studies that Kossel s theory was more appropriate... 

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. 

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