Lewis electron-dot structures

B—The Lewis (electron-dot) structure has five bonding pairs around the central Sb and no lone pairs. VSEPR predicts this number of pairs to give a trigonal bipyramidal structure. 

The Lewis electron-dot structure is a way of representing an element and its valence electrons. 

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,)... 

Vitamin C (ascorbic acid) has the following connections among atoms. Complete the Lewis electron-dot structure for vitamin C, and identify any multiple bonds. 

The meaning of this term is easy to grasp in a qualitative, intuitive way an ideal single bond has a bond order of one, and ideal double and triple bonds have bond orders of two and three, respectively. Invoking Lewis electron-dot structures, one might say that the order of a bond is the number of electron pairs being shared between the two bonded atoms. Calculated quantum mechanical bond orders should... 

Shown below are the Lewis electron dot structures for five elements sulfur (S), chlorine (Cl), argon (Ar), potassium (K), and calcium (Ca). Answer the questions below about these structures. 

Which of the above Lewis electron dot structures is the same as the Lewis electron dot structure for the ion S2 Explain your answer. 

Draw Lewis electron-dot structures of simple compounds. 

Problem 1.7 Use the Lewis-Langmuir octet rule to write Lewis electron-dot structures for (a) HCN, (b), CO2, (c) CCI4 and (cf) C2Hf,0. -4... 

Valence shell electron pair repulsion theory (VSEPR) provides a method for predicting the shape of molecules, based on the electron pair electrostatic repulsion. It was described by Sidgwick and Powell" in 1940 and further developed by Gillespie and Nyholm in 1957. In spite of this method s very simple approach, based on Lewis electron-dot structures, the VSEPR method predicts shapes that compare favorably with those determined experimentally. However, this approach at best provides approximate shapes for molecules, not a complete picture of bonding. The most common method of determining the actual stmctures is X-ray diffraction, although electron diffraction, neutron diffraction, and many types of spectroscopy are also used. In Chapter 5, we will provide some of the molecular orbital arguments for the shapes of simple molecules. 

Write a Lewis (electron-dot) structure for acetonitrile, C2H3N, which contains a carbon-nitrogen triple bond. How many electrons does the nitrogen atom have in its Outer shell How many are bonding, and how many are nonbonding ... 

Complete the Lewis electron-dot structure of caffeine, showing all lone-pair electrons, and identify the hybridization of the indicated atoms. 

Draw a Lewis electron-dot structure for each of the molecules in Problem 2.40, indicating any unshared electron pairs. 

I See the Saunders Interactive General Chemistry CD-ROM, Screen 9.4, Lewis Electron Dot Structures. 

Draw Lewis electron dot structures for the ions listed. (Chapter 2)... 

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