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Electronic Structure and Bonding. Acids and Bases Chapter 1. Contents of Chapter 1. Bonding, Lewis Structures Atomic & Molecular Orbitals Hybrid Orbitals Single Bonds Multiple Bonds Dipole Moments Polar Bonds Acid/base Theory. Ionic Bonds. Covalent Bonds. covalent bond.
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Electronic Structure and Bonding. Acids and BasesChapter 1 Chapter 1
Contents of Chapter 1 • Bonding, Lewis Structures • Atomic & Molecular Orbitals • Hybrid Orbitals • Single Bonds • Multiple Bonds • Dipole Moments Polar Bonds • Acid/base Theory Chapter 1
Ionic Bonds Chapter 1
Covalent Bonds covalent bond Chapter 1
Polar Covalent Bonds Chapter 1
Polar Covalent Bonds • There is a continuum of bonding types Chapter 1
Electronegativity Chapter 1
Lewis Structures • The chemical symbols we have been using in which valence electrons are shown as dots are called Lewis structures Chapter 1
Drawing Lewis Structures • Write the symbols for the elements in the correct structural order • Consider nitric acid, HNO3 Chapter 1
Sticks and Eyeballs • Bonds + Lone Pairs = 4 (Octet Rule) • Exceptions: H has 1 bond, B has 3 bonds • Bonds: Count spaces from noble gas • Convert bond to LP is (-), LP to bond is (+) • Exceptions: C(+), B(-) Chapter 1
Formal Charges • Subtract the number of assigned electrons from the number of valence electrons for an uncombined atom of the same element 6 - 6 = 0 1 - 1 = 0 6 - 7 = -1 6 - 6 = 0 5 - 4 = +1 Chapter 1
Condensed Structural Formulas • Kekulé formulas also are called structural formulas • Often, structural formulas are condensed becomes Chapter 1
1s and 2s Orbitals Chapter 1
2p Orbitals Chapter 1
Molecular Orbital From p Electrons • Molecular orbitals also can be formed from p orbitals Chapter 1
Hybrid Orbitals • Methane, CH4, has four equivalent carbon-hydrogen bonds Chapter 1
Hybridization • Theory: Mix the 2s orbital with the three 2p orbitals to form four equivalent hybrid orbitals Chapter 1
Hybridization - Tetrahedral Carbon • The sp3hybrid orbital on carbon also can bond with another sp3hybrid orbital from a neighboring carbon to form a carbon-carbon single bond Chapter 1
sp2Hybridization in Ethene • The carbon-carbon bond formed from the overlap of an sp2 orbital on one carbon with an sp2 orbital on a neighboring carbon atom results in an orbital which is cylindrically symmetric about the carbon-carbon axis Chapter 1
sp2Hybridization in Ethene • A second bond is formed between the two carbon atoms via the side-by-side overlap of the remaining (un-hybridized) p orbitals • Electron density accumulates above and below the carbon-carbon axis Chapter 1
sp Hybridization in Ethyne • The overlap of the sp hybrid orbitals forms a bond Chapter 1
sp Hybridization in Ethyne • The remaining p orbitals overlap side-by-side, forming bonds with electron density above and below the carbon-carbon axis as well as in front and in back Chapter 1
Summary of Orbital Hybridization Chapter 1
Curved Arrows • Curved arrows represent motions of PAIRS of electrons • Tail of arrows is ORIGINAL location of electrons • Point of arrow is FINAL location of electrons Chapter 1
Acids and Bases in Organic Reactions • H’s in organic compounds have varying degrees of acidity Chapter 1
Acidity and Structure • Electronegative atoms or groups increase acidity Chapter 1
acid H+ + base D pKa as a Stability Parameter • pKa tracks relative potential E of conj base • Strong acids: low pKa = stable conj base • Weak acids: high pKa = unstable conj base pKaDGº Chapter 1
Examples of Organic Acid - Base Reactions • To use pKa as a PE write it under base form • Rxn shifts to side with lowest PE • Textbook shows pKa valuesunder acids Chapter 1