Bond Angles and Shape

In a planetary model of an atom, negatively charged electrons (-1 each) are arranged around a positively charged nucleus (+Z = nuclear charge) in a series of shells that look like orbits. 

Electrons DO NOT orbit the nucleus like the planets orbit the sun. In ChemActivity 3 we will study a more complex model in which electrons are described as inhabiting 3-dimensional regions of space called orbitals (Is, 2s, 2p, 2py, 2pz, 3s, etc.). 

(E) How many total electrons does an oxygen atom have, and how could you find the answer to 

Bonding electron domain = shared valence electrons (2,4, or 6e ) localized between two core atoms 3 types Single Bond (1 pair, 2 electrons) Double Bond (2 pairs, 4 e ) Triple Bond (3 pairs, 6 e ) 

Non-bonding electron domain ( lone pair ) = pair of valence electrons (2 e ) not involved in a bond 

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Bond Angles and Shapes of Molecules Polar and Nonpolar Molecules Quantum or Wave Mechanics... 

Bond angle determines the shape around any atom bonded to two other atoms. To determine the bond angle and shape around a given atom, we must first determine how many groups surround the atom. A group is either an atom or a lone pair of electrons. Then we use the valence shell electron pair repulsion (VSEPR) theory to determine the shape. VSEPR is based on the fact that electron pairs repel each other thus ... 

Indicate the bond angle and shape about each central atom. H H H H... 

A student who missed this class needs to know how to predict the bond angles and shape of a molecule from looking at its bond-line representation. Write a concise but complete explanation for this student. 

UNIQUAC is significant because it provides a means to estimate multicomponent interactions using no more than binary interaction experimental data, bond angles, and bond distances. There is an implicit assumption that the combinatorial portion of the model, ie, the size and shape effects, can be averaged over a molecule and that these can be directly related to molecular surface area and volume. This assumption can be found in many QSAR methods and probably makes a significant contribution to the generally low accuracy of many QSAR prediction techniques. 

Draw a line-bond structure for propane, CH3CH2CH3. Predict the value of each bond angle, and indicate the overall shape of the molecule. 

For each of the following species, write the Lewis structure, predict the shape and hybridization about each central atom, give the bond angles, and state whether it is polar or nonpolar (a) SnCl3 (b) TeO, (c) NO (d) IC1,. 

Table 9 3 summarizes the relationships among steric number, electron group geometry, and molecular shape. If you remember the electron group geometry associated with each steric number, you can deduce molecular shapes, bond angles, and existence of dipole moments. 

Conformational analysis consists in investigations concerned with the determination of molecular shapes, commonly described by bond angles and bond lengths. Among the various methods generally used68 for the estimation of these parameters, X-ray analysis provides... 

As shown in Fig. 4.69, the HfFLi- alkene complex exhibits expected parallels with the HfFLi- H2 complex (Fig. 4.59), both in terms of molecular shape and in terms of valence interactions. The characteristic features of such weak dative bonding include long Hf—C distances (2.82 A), normal C=C bond length (1.34 A), planar alkene bond angles, and small binding energy (15.1 kcalmol-1)-... 

The contents of this chapter are fundamental in the applications of molecular orbital theory to bond lengths, bond angles and molecular shapes, which are discussed in Chapters 3-6. This chapter introduces the principles of group theory and its application to problems of molecular symmetry. The application of molecular orbital theory to a molecule is simplified enormously by the knowledge of the symmetry of the molecule and the group theoretical rules that apply. 

Table 5.1 The basic shapes, bond angles and hybridizations adopted by various numbers of o pairs of electrons...

The AO s of carbon can hybridize in ways other than sp as shown in Fig. 2-7. Repulsion between pairs of electrons causes these HO s to have the maximum bond angles and geometries summarized in Table 2-2. The sp and sp HO s induce geometries about the C s as shown in Fig. 2-8. Only a bonds, not v bonds, determine molecular shapes. 

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