Chapter 1: Structure and Bonding mcmurry

Coverage: 1. Electron Configurations. 2. Lewis Structures 3. Covalent and Ionic bonds 4. Atomic and Molecular Orbitals 5. Hybridization Goals: Write the electron configuration for any element in the periodic table. Write Lewis line bond structures for simple organic molecules. Know how to calculate formal charges on atoms. Know the definitions of a sigma and pi bonds. Draw energy diagrams for formation of pi and sigma bonds. Predict the number of sigma and pi bonds in a molecule. Predict the hybridization of an atom in a molecule. Predict the approximate bond angles in a molecule.

Hybridization of Atomic Orbitals 1.AOs on a single atom mix to form new, hybrid orbitals. These hybrid orbitals have characteristics of both s and p orbitals. 2.Provides a means of explaining observed bond angles in organic molecules.

1-4 Methane sp 3 The carbon atom is sp 3 hybridized to obtain tetrahedral geometry. All bond angles are equal at E __ s __ __ __ p __ __ __ __ __ __ __ __sp 3 Promote e- Mix orbitals

1-5 s + 3 p = 4 sp 3 orbitals D:\rw32b2a.exe

1-6 Ethylene sp 2 The carbon atom is sp 2 hybridized to obtain trigonal planar geometry E __ s __ __ __ p __ __ __ __ __ p __ __ __ sp 2 hybrid Promote e- Mix orbitals

1-7 s + 2 p = 3 sp 2 orbitals sp 2 Hybridization There is one p orbital left over, and it would be along the z axis.

1-8 Orbital Picture of Ethylene D:\rw32b2a.exe

1-9 Acetylene 180 o sp E __ s __ __ __ p __ __ __ __ __ __ p __ __ sp hybrid promote e- Mix orbitals D:\rw32b2a.exe

1-10 s + p = sp + sp Two sp orbitals Remember, there are two p orbitals leftover and these would be located on the y and z axes. y z x Each sp orbital possesses 50% s character and 50% p character.

1-11 s + p = sp + sp Two sp orbitals Remember, there are two p orbitals leftover and these would be located on the y and z axes. y z x Each sp orbital possesses 50% s character and 50% p character.

Orbital Picture of Acetylene D:\rw32b2a.exe