Lewis electronic formulas

In 1913, G. N. Lewis suggested that a line connecting two singlet-coupled electrons makes up one bond, giving birth to the concept of the electron pair bond and the Lewis electronic formula of a molecule. In Deciphering... 

The number of covalent bonds formed by an atom is termed its COVALENCY. The covalency of an atom is equal to the number of electrons the atom needs to become isoelectronic with a noble gas. Some of the more common elements have the following covalencies when they follow the octet rule and also have no charge hydrogen and the halogens, 1 oxygen and sulfur, 2 nitrogen and phosphorus, 3 carbon and silicon, 4. LEWIS ELECTRONIC FORMULAS, in which bonds and unshared electrons are shown, are given for a few typical compounds of these elements ... 

This method of calculating oxidation numbers requires a prior knowledge of Lewis electronic formulas. Such formulas may be difficult to write for molecules and ions containing transition elements. Fortunately, rules derived from the method just discussed can be used to get oxidation numbers directly from molecular or empirical formulas ... 

Lewis s theory and Heitler and London s extension permitted the reasonably certain attribution of specific electronic formulas to a great many compounds. In other cases, however, it was possible to set up a number of alternative electronic formulas for a molecule or crystal, and often no sound argument could be advanced supporting any one of them against the others. For example, Lewis gave the perchlorate ion the... 

For each molecule, ion, or free radical that has only localized electrons, it is possible to draw an electronic formula, called a Lewis structure, that shows the location of these electrons. Only the valence electrons are shown. Valence electrons may be found in covalent bonds connecting two atoms or they may be unshared. The student must be able to draw these structures correctly, since the position of electrons changes in the course of a reaction, and it is necessary to know where the electrons are initially before one can follow where they are going. To this end, the following rules operate ... 

The Lewis dot formula predicts 4 regions of high electron density around the central N atom, a tetrahedral electronic geometry and a pyramidal molecular geometry. The N atom has sp3 hybridization (Sections 8-8 and 28-14). The three-dimensional structure is shown below. 

The Lewis dot formulas for the two resonance structures (one is shown) predicts 3 regions of high electron density for the N atom, and a trigonal planar electronic and molecular geometry about the N atom. The N atom has sp2 hybridization (Section 28-16). The three-dimensional structure is shown on the next page. 

Have you ever wondered how to draw the structures of compounds For example, compounds such as CCI4, PBr3 or ions such as SO. To draw the structural formulae we will use the Lewis (electron dot) notation. 

Lewis electron-dot structure The Lewis electron-dot structure is a structural formula that represents the element and its valence electrons. 

We can use Lewis dot formulas to represent the transfer of electrons in the formation of ionic compounds. For example, the formation of the ionic compound sodium fluoride, NaF, can be represented using Lewis dot formulas and valence electron conflgurations ... 

Le Chatelier s Principle principle that says when a system is at equilibrium and a change is imposed on the system that the system will shift to reduce the change Lewis Electron Dot Formula a diagram showing how the valence electrons are distributed around an atom or distributed in a molecule... 

Molecular formulas merely include the kinds of atoms and the number of each in a molecule (as C4H , for butane). Structural formulas show the arrangement of atoms in a molecule (see Fig. 1-1). When unshared electrons are included, the latter are called Lewis (electron-dot) structures [see Fig. 1-1(/)]. Covalences of the common elements—the numbers of covalent bonds they usually form—are given in Table 1-1 these help us to write Lewis structures. Multicovalent elements such as C, O. and N may have multiple bonds, as shown in Table 1-2. In condensed structural formulas all H s and branched groups are written immediately after the C atom to which they are attached. Thus the condensed formula for isobutane [Fig. l-l(f>)) is CH,CH(CH,)... 

Exercise 2-1 Draw the Lewis electron-pair structure of 2-propanone (acetone) clearly showing the bonding and nonbonding electron pairs in the valence shell of each atom. Draw structural formulas for other compounds having the composition C3H60 that possess... 

Draw Lewis electron-pair structures for the following substances whose structural formulas are given. Use distinct, correctly placed dots for the electrons and show... 

This book contains large numbers of Lewis structural formulas. Frequendy we shall not write out the full Lewis structure unshared pairs of electrons not shown explicitly are implied. When there are two or more contributing structures, we shall show them all only if that is essential to the point being illustrated again, it will be assumed that the reader will understand that the missing structures are implied. 

In the water molecule, the central atom is O, and the Lewis electron dot formula predicts that there will be two pairs of nonbonding electrons. The oxygen atom will therefore be tetrahedrally coordinated, even though the number of atoms bound to it is only two. The two nonbonding orbitals are very much like the bonding ones, except that there are no other atoms at their far ends. 

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