II MOLECULAR COMPOUNDS Chemical Bonding C Johannesson IV
II. MOLECULAR COMPOUNDS Chemical Bonding C. Johannesson IV
A. Energy of Bond Formation • Potential Energy • based on position of an object • low PE = high stability C. Johannesson
A. Energy of Bond Formation • Potential Energy Diagram attraction vs. repulsion no interaction increased attraction C. Johannesson
A. Energy of Bond Formation • Potential Energy Diagram attraction vs. repulsion increased repulsion balanced attraction & repulsion C. Johannesson
A. Energy of Bond Formation • Bond Energy • Energy required to break a bond Bond Energy Bond Length C. Johannesson
A. Energy of Bond Formation • Bond Energy • Short bond = high bond energy C. Johannesson
B. Lewis Structures • Electron Dot Diagrams • show valence e- as dots X • distribute dots like arrows in an orbital diagram • 4 sides = 1 s-orbital, 3 p-orbitals • EX: oxygen 2 s 2 p O C. Johannesson
B. Lewis Structures • Octet Rule • Most atoms form bonds in order to obtain 8 valence e • Full energy level stability ~ Noble Gases Ne C. Johannesson
B. Lewis Structures • Nonpolar Covalent - no charges • Polar Covalent - partial charges + C. Johannesson +
Sigma and Pi bonds • Sigma Bonds σ • Valence orbitals overlap and electron pair is shared in the area centered between the 2 atoms • 2 s orbitals; an s and a p orbital or 2 p orbitals • Pi Bonds π • Electron pair is shared above and below the line that represents where 2 atoms are joined • Due to shape of the p orbital • Not as strong as sigma because parallel orbitals are overlapping • Single bond – 1 sigma bond (1 shared pair of e-) • Double bond – 1 sigma and 1 pi bond (2 shared pairs) • Triple bond – 1 sigma and 2 pi bonds (3 shared pairs) C. Johannesson
C. Molecular Nomenclature • Prefix System (binary compounds) 1. Less e-neg atom comes first. 2. Add prefixes to indicate # of atoms. Omit monoprefix on first element. 3. Change the ending of the second element to -ide. C. Johannesson
C. Molecular Nomenclature PREFIX monoditritetrapentahexaheptaoctanonadeca- NUMBER 1 2 3 4 5 6 7 8 9 10 C. Johannesson
C. Molecular Nomenclature z. CCl 4 z. N 2 O z. SF 6 C. Johannesson
C. Molecular Nomenclature zarsenic trichloride zdinitrogen pentoxide ztetraphosphorus decoxide C. Johannesson
C. Molecular Nomenclature • The Seven Diatomic Elements Br 2 I 2 N 2 Cl 2 H 2 O 2 F 2 H N O F Cl Br I C. Johannesson
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