BCHM-3050 Lecture Notes - Lecture 1: Relative Permittivity, Intermolecular Force, Clathrate Compound
19 May 2018
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Department
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Water and its unique properties
Has 2 H bond donor and acceptor sites (two lone pairs connected to
oxygen)
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Permanent dipole
Remember: difference in charges between atoms in molecule
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Bond angle: 104.5 degrees. Tetrahedral.
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High heat capacity
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Density is greater in liquid
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High dielectric constant
Remember: the screen between molecules and their charges
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Water = universal solvent
Able to dissolve more substances than other liquids
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Can form many intermolecular forces w other molecules
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Hydrophilic v Hydrophobic
Hydrophilic: molecules attracted to water
LOVE water
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Hydrophobic: molecules repel water
HATE water
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Preference for or against water plays role in determining function in
aqueous environment
Ex. A cell
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NOTE: like dissolves like
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Hydrophilic
Dissolution: mixing solvent and solute
Favorability for this process is determined by type and bond energy
of intra and intermolecular forces b/w solute and solvent
Basically! Whether a solute feels inclined to dissolve in water
or not depends on the forces b/w water and the solute
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Solubility: measures how much of solute will dissolve in solvent
Units of grams per 100 mL
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Hydrophobic
Clathrate: structures that surround nonpolar surface areas or molecules
Nonpolar solute in polar solvent
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Like a trap
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Trapping nonpolar molecules in polar molecules decreases entropy of the
solvent (+∆G)
Remember: entropy is degree of spontaneity in system. How things
happen randomly. (-∆G)
Decreasing entropy is unfavorable
Would be something that would not happen naturally w/o
outside input.
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The product would not be produced naturally
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Hydrophobic effect: used by macromolecules (proteins)
Stabilizes structures by driving nonpolar chains together during
folding
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Allows solvent entropy to remain higher
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Amphipathic
Amphipathic: contain hydrophobic and hydrophilic groups
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Can form monolayer, micelle or bilayer
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Phospholipid bilayer
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Chapter 2: Water
Tuesday, May 15, 2018
6:20 PM
Document Summary
Has 2 h bond donor and acceptor sites (two lone pairs connected to oxygen) Remember: difference in charges between atoms in molecule. Remember: the screen between molecules and their charges. Able to dissolve more substances than other liquids. Can form many intermolecular forces w other molecules. Preference for or against water plays role in determining function in aqueous environment. Favorability for this process is determined by type and bond energy of intra and intermolecular forces b/w solute and solvent. Whether a solute feels inclined to dissolve in water or not depends on the forces b/w water and the solute. Solubility: measures how much of solute will dissolve in solvent. Clathrate: structures that surround nonpolar surface areas or molecules. Trapping nonpolar molecules in polar molecules decreases entropy of the solvent (+ g) Remember: entropy is degree of spontaneity in system. Would be something that would not happen naturally w/o outside input. Stabilizes structures by driving nonpolar chains together during folding.
