化学成键英文版.ppt

Basic Chemical Bonding Looking Back at Chemical Bonding Lewis Theory Lewis Dot Structure Lewis Dot Structure – 2 Lewis Dot in Covalent Bond Polar Covalent Bond Electronegativity Periodic Table of Electronegativity Covalent and Ionic Bonds Electron Density of a Polar Bond Li–H Writing Lewis Dot Structures Formal Charge Find Formal Charge Resonance Draw Resonance Structures Exceptions to the Octet Rule Bond Properties VSEPR Theory Shape of Molecules Chemistry and Molecular Shapes Structures with Multiple Covalent Bonds Molecules with more than one central atom Dipole Moment Dipole moment of H2O Dipole moment and Molecular Shape Review 1 Review 2 Review 3 Basic Chemical Bonding Cubane Dodecahedrane Side and top views of a single-wall exohydrogenated carbon nanotube Molecules are artwork – just beautiful! Bonding must be electric nature. 1852, E. Frankland proposed the valence concept, using “–” for valence. 1857, F.A. Kekule figured out the structure of benzene C6H6. 1874 J.H. vant Hoff and le Bel postulated the tetrahedral arrangement of 4 bonds around carbon. 1916 G.N. Lewis propsed the dot symbol for valence electrons 1923 G.N. Lewis wrote Valence and the structure of atoms and molecules. 1939 L. Pauling wrote The nature of chemical bond 1940 N.V. Sidgwick and H.E. Powell studied the lone pairs of valence electrons. The attraction between electrons of one atom to the nucleus of another atom contribute to what is known as chemical bonds. G.N. Lewis (1875-1946) recognized valence (outmost) electrons fundamental to bondingelectron transfer resulting in ionic bondssharing electrons resulting in covalent bondsatoms tend to acquire a noble-gas electronic configurations Lewis wrote in a memorandum dated March 28, 1902 Lewis Paper of 1916 In this paper, Lewis begins by using cubes, but he moves away from them by the end of the paper. Here is how he visualized the elements lithium through fluorine: Please illustrate modern Lewis dot structures of periods 2