Lecture 9 - Lecture 9 Special types of bonds Hydrogen...

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Lecture 9: Special types of bonds Hydrogen bonding and other “weak interactions” H-bonding is a special case of a dipole-dipole interaction Responsible for the special properties of water and other liquids like antifreeze, maple syrup Responsible for the shapes of most of the important biological molecules like DNA, enzymes, cellulose, on and on There is a molecular orbital picture of hydrogen bonding. The molecular orbitals of the two interacting species can mix to make a new set of orbitals with slightly adjusted energies. Other kinds of dipole interactions include direct and induced electrostatic attractions. The weakest is the induced dipole-induced dipole interaction. In this case, the presence of a neighboring molecule causes a slight distortion in the electron clouds (and the molecular orbitals), resulting in a very small attraction. However, this is sufficient to make totally nonpolar species condense into liquids and solids at low enough temperatures. Ionic bonding
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This note was uploaded on 09/29/2009 for the course ME 530.230 taught by Professor Katz during the Spring '09 term at Johns Hopkins.

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Lecture 9 - Lecture 9 Special types of bonds Hydrogen...

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