Shapes of atomic Orbitals for Electrons Four different kinds of orbitals for electrons based on those derived for a hydrogen atom Denoted s, P, d, and f s and p orbitals most important in organic chemistry s orbitals: spherical, nucleus at center p orbitals: dumbbell-shaped, nucleus at middle
Shapes of Atomic Orbitals for Electrons • Four different kinds of orbitals for electrons based on those derived for a hydrogen atom • Denoted s, p, d, and f • s and p orbitals most important in organic chemistry • s orbitals: spherical, nucleus at center • p orbitals: dumbbell-shaped, nucleus at middle
1.3 Development of chemical Bonding Theory化学键理论的发展 Kekule and Couper independently observed that carbon al ways has four bonds van't Hoff and le bel proposed that the four bonds of carbon have specific spatial directions Atoms surround carbon as corners of a tetrahedron Note that a dashed line indicates a bond is behind the page Note that a wedge indicates a bond is coming forward
1.3 Development of Chemical Bonding Theory 化学键理论的发展 • Kekulé and Couper independently observed that carbon always has four bonds • van't Hoff and Le Bel proposed that the four bonds of carbon have specific spatial directions – Atoms surround carbon as corners of a tetrahedron Note that a wedge indicates a bond is coming forward Note that a dashed line indicates a bond is behind the page
Atoms form bonds because the compound that results is more stable than the separate atoms Stable molecule results at completed shell, octet(eight dots) for main-group atoms(two for hydrogen)
• Atoms form bonds because the compound that results is more stable than the separate atoms • Stable molecule results at completed shell, octet (eight dots) for main-group atoms (two for hydrogen)
1 4 The nature of the chemical Bond: Ionic Bonds 化学键的种类:离子键 Ionic bonds in salts form as a result of electron transfers Lewis structures shown valence electrons of an atom as dots Hydrogen has one dot, representing its Is electron Carbon has four dots(2s 2p2)
1.4 The Nature of the Chemical Bond:Ionic Bonds 化学键的种类:离子键 • Ionic bonds in salts form as a result of electron transfers • Lewis structures shown valence electrons of an atom as dots – Hydrogen has one dot, representing its 1s electron – Carbon has four dots (2s 2 2p 2 )
1. 5 The nature of the Chemical bond p7 Covalent bonds 化学键的种类共价键 In 1916GN Lewis proposed that atoms combine in order to achieve a more stable electron configuration. Organic compounds have covalent bonds from sharing electrons An electron pair that is shared between two atoms constitutes a covalent bond Maximum stability results when an atom is isoelectronic with a noble gas[octet(L,)
1.5 The Nature of the Chemical Bond : Covalent Bonds 化学键的种类:共价键 • In 1916 G. N. Lewis proposed that atoms combine in order to achieve a more stable electron configuration. Organic compounds have covalent bonds from sharing electrons • An electron pair that is shared between two atoms constitutes a covalent bond • Maximum stability results when an atom is isoelectronic with a noble gas[octet(八隅体)] p.7