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Chapter 12
Chemical Bonding II: Additional Aspects
 
 
 
Movie
Title
 Movie
Caption
 The change in potential energy as a function of H-H bond distance for H2 is illustrated in this animation.
Notes
 H2 Bond Formation. As two H atoms approach each other to form an H2 molecule their orbitals begin to overlap, resulting in a decrease in energy as the electron density between the nuclei increases. When the atoms are very close thenuclei repel each other, causing an increase in energy. The observed bond length is the distance at which the attractive and repulsive forces are balanced.
Movie
Title
 Movie
Caption
 Hybridization of hydrogen-like s and p orbitals
Notes
 Hybridization. Hybrid orbitals are formed by mixing s, p and d orbitals. Mixing an s and a px orbital produces two sp hybrid orbitals which point in opposite directions along the x axis. The s, px and py orbitals combine to form three equivalent sp2 hybrid orbitals which point toward the corners of a triangle in the x-y plane. Mixing of an s and three p orbitals gives four sp3 hybrid orbitals which are directed toward the apices of a tetrahedron.
12.1
Title
 12-2
Caption
 Energy of interaction of two hydrogen atoms. This graph shows •Êa zero of energy when two H atoms are separated by great distances; •Êa drop in potential energy (net attraction) as the two atoms approach each other; •Êa minimum in potential energy (2436 kJ/mol) at a particular internuclear distance (74 pm) corresponding to the stable molecule H2; •Êan increase in potential energy as the atoms approach more closely
Notes
  
12.3
Title
 12-3
Caption
 Bonding and structure of the PH3 molecule-Example 12-1 illustrated. Orbitals with a single electron are gray. Those with electron pairs are in color. Only bonding orbitals are shown. The 1s orbitals of three H atoms overlap with the three 3p orbitals of the P atom
Notes
  
12.5
Title
 12-5
Caption
 The sp3 hybridization scheme.
Notes
  
12.6
Title
 12-6
Caption
 Bonding and structure of CH4. The four carbon orbitals are sp3 hybrid orbitals (violet). Those of the hydrogen atoms (red) are 1s. The structure is tetrahedral, with HOCOH bond angles of 109.5° (more precisely, 109°28’)
Notes
  
12.7
Title
 12-7
Caption
 sp3 hybrid orbitals and bonding in NH3. An sp3 hybridization scheme yields a molecular geometry in close agreement with what is observed experimentally. The portion of the figure exclusive of the orbital occupied by a lone pair of electrons is a trigonal pyramid
Notes
  
12.8
Title
 12-8
Caption
 The sp2 hybridization scheme
Notes
  
12.9
Title
 12-9
Caption
 The sp hybridization scheme.
Notes
  
12.10
Title
 12-10
Caption
  
Notes
 The formation on an sp hybrid orbital
12.11a,b
Title
 12-11
Caption
 sp3d and sp3d2 hybrid orbitals.
Notes
  
12.11.2UN
Title
 PP 446
Caption
 XeF4 molecular diagram
Notes
 XeF4 molecule
12.12
Title
 12-12
Caption
 Sigma (s) and pi (p) bonding in C2H4. The reddish purple orbitals are sp2 hybrid orbitals and the blue orbitals, 2p. The sp2 hybrid orbitals overlap along the line joining the bonded atoms-a s bond. The 2p orbitals overlap in a side-to-side fashion and form a p bond.
Notes
  
12.13
Title
 12-13
Caption
 Ball-and-stick model of ethylene, C2H4. The HOCOH and COCOH bond angles are 120°. The model also distinguishes between the s bond between the C atoms (the straight plastic tube) and the p bond extending above and below the plane of the molecule. The picture of the p bond suggested by the white plastic “arches” is somewhat distorted, but the model does convey the idea that the p bond places a high electron charge density above and below the plane of the molecule
Notes
  
12.14
Title
 12-14
Caption
 Sigma (s) and pi (p) bonding in C2H2. The s bond framework joins the atoms HOCOCOH through 1s orbitals of the H atoms and sp orbitals of the C atoms. There are two p bonds. Each p bond consists of two parallel cigar-shaped segments. The four segments shown actually merge into a hollow cylindrical shell with the carbon-to-carbon s bond as its axis.
Notes
  
12.15
Title
 12-15
Caption
 Bonding and structure of the H2CO molecule-Example 12-2 illustrated. The orbital set sp2 1 p is used for the C atom, 1s orbitals for H, and two half-filled 2p orbitals for O. For simplicity, only bonding orbitals of the valence shells are shown.
Notes
  
12.16
Title
 12-16
Caption
  
Notes
 Bonding in H2Co -- a schematic representation
12.17
Title
 12-17
Caption
 Bonding and structure of HCOOH-Example 12-3 illustrated
Notes
  
12.18
Title
 12-18
Caption
  
Notes
 Formation of bonding and antibonding orbitals
12.19
Title
 12-19
Caption
 The interaction of two hydrogen atoms according to the molecular theory. The energy of the s1s bonding molecular orbital is lower, and that of the s1s* antibonding molecular orbital is higher, than the energies of the 1s atomic orbitals. Electron charge density in a bonding molecular orbital is high in the internuclear region. In an antibonding orbital it is high in parts of the molecule away from the internuclear region.
Notes
  
12.20
Title
 12-20
Caption
 Molecular-orbital diagrams for the diatomic molecules and ions of the first-period elements. The 1s energy levels of the isolated atoms are shown to the left and right of each diagram. The line segments in the middle represent the molecular orbital energy levels-lower than the 1s levels for s1s and higher for s1s*
Notes
  
12.21
Title
 12-21
Caption
  
Notes
 Formation of bonding and antibonding orbitals from sp orbitals
12.22
Title
 12-22
Caption
 Molecular orbitals formed from 2p atomic orbitals. These diagrams suggest the electron charge distributions for the several orbitals. They are not exact in all details. Nodal planes for antibonding orbitals are represented by broken lines.
Notes
  
12.24
Title
 12-24
Caption
 Molecular orbital diagrams for actual and hypothetical diatomic molecules of the second-period elements. In all cases the s1s and s1s* molecular orbitals are filled but not shown
Notes
  
12.25
Title
 12-25
Caption
  
Notes
 Resonance in benzene molecule and the Kekule structures
12.26a-c
Title
 12-26
Caption
 Bonding in benzene, C6H6, by the valence-bond method. (a) Carbon atoms use sp2 and p orbitals. Each carbon atom forms three s bonds, two with neighboring C atoms in the hexagonal ring and a third with an H atom. (b) The overlap in sidewise fashion of 2p orbitals produces three p bonds. Thus there are three double bonds (s 1 p) between carbon atoms in the ring. (c) Because the three p bonds are delocalized around the benzene ring, the molecule is often represented through a hexagon with an inscribed circle.
Notes
  
12.27
Title
 12-27
Caption
  
Notes
 Pi molecular orbital diagram for C6H6.
12.28
Title
Caption
 Molecular orbital representation of p bonding in benzene. A computer-generated model of the benzene molecule. The planar s bond framework is clearly visible. The p orbitals above and below the C and H plane are highlighted
Notes
  
12.29
Title
 12-29
Caption
 Structure of the ozone molecule O3. (a) The s bond framework and the assignment of bond pair (S) and lone pair (S) electrons to sp2 hybrid orbitals are discussed in items 1 and 2 on page 408. (b) The p molecular orbitals and assignments of electrons to them are discussed in items 3 and 4.
Notes
  
12.30
Title
 12-30
Caption
  
Notes
 Pi bonding orbitals of the ozone molecule, O3
12.31
Title
 12-31
Caption
 The electron sea model of metals. A network of positive ions is immersed in a “sea of electrons,” derived from the valence shells of the metal atoms and belonging to the crystal as a whole. One particular ion (red), its nearest neighboring ions (brown), and nearby electrons in the electron sea (blue) are emphasized. At the bottom of the figure, a force is applied (from left to right). The highlighted cation is unaffected; its immediate environment is unchanged. The electron sea model explains the ease of deformation of metals
Notes
  
12.32
Title
 12-32
Caption
 Formation of an energy band in lithium metal. As more and more Li atoms are added to the growing “molecule,” Li2, Li3, . . . , additional energy levels are added and the spacing between levels becomes increasingly smaller. In an entire crystal of N atoms, the energy levels merge into a band of N closely spaced levels. The lowest N/2 levels are filled with electrons and the upper N/2 levels are empty
Notes
  
12.33
Title
 12-33
Caption
 Metals, semiconductors, and insulators as viewed by band theory. (a) In some metals the valence band (blue) is only partially filled (e.g., the half-filled 3s band in Na). The valence band also serves as a conduction band (outlined in black). (b) In other metals the valence band is full, but a conduction band overlaps it (e.g., the empty 3p band of Mg overlaps the full 3s valence band). (c) In a semiconductor the valence band is full, and the conduction band is empty. The energy gap (DE) between the two is small enough, however, that some electrons make the transition between the two just by acquiring thermal energy. (d) In an insulator the valence band is filled with electrons, and a large energy gap (DE) separates the valence band from the conduction band. Few electrons can make the transition between bands, and the insulator does not conduct electricity.
Notes
  
12.34
Title
 12-34
Caption
 p- and n-type semiconductors. In a semiconductor with donor atoms (for example, P in Si), the donor level lies just beneath the conduction band. Electrons (•) are easily promoted into the conduction band. The semiconductor is of the n-type. In a semiconductor with acceptor atoms (for example, Al in Si), the acceptor level lies just above the valence band. Electrons (•) are easily promoted to the acceptor level, leaving positive holes (•) in the valence band. The semiconductor is of the p-type.
Notes
  
12.35
Title
 12-35
Caption
 A photovoltaic (solar) cell using silicon-based semiconductors.
Notes
  
12.36
Title
 12-36
Caption
 schematic of a photoelectron spectrometer
Notes
  
12.37
Title
 12-37
Caption
  
Notes
 The photelectron spectrum of Ne
12.38
Title
 12-38
Caption
  
Notes
 The photelectron spectrum of N2 and Co.
P 456
Title
 P 456
Caption
  
Notes
 The comuted molecular orbitals of F2.
P 459
Title
 P 459
Caption
  
Notes
 MO diagrams for CO molecule
P 461
Title
 P 461
Caption
  
Notes
 Picture of Dame Kathleen Lonsdale.