What Makes Water So Special? Polarity- waters bent shape creates δ- and δ+ areas in the molecule
Intermolecular Forces forces of attraction that occur between molecules of a substance Hydrogen Bonds Van Der Walls Forces Dipole-Dipole Interactions Dispersion Forces
Intermolecular Forces 1. Hydrogen Bonding- strongest intermolecular force, 2. 5% of covalent bond. 3. hydrogen is bonded to a strongly electronegative atom (O, N, F) and is also attracted to lone electron pairs on a neighboring molecule
Intermolecular Forces Dipole interactions- van der Waals forces seen in polar molecules as a result of partial charge distribution
Intermolecular Forces dispersion forces- weakest van der Waals force caused by motion of electrons and increase as # of electrons increases
Properties of Water Surface Tension- water has an unusually high surface tension because its molecules are strongly attracted to one another (as opposed to their attraction to air molecules)
Properties of Water Heat Capacity- we are able to inhabit this planet because it takes a lot of energy to raise the temperature of water
Properties of Water Density of Ice- decreases from 4 to 0°C because molecules become locked in place as kinetic energy is decreased
Water as a Solvent Ionic and Polar Compounds- tend to become solvated in water to form aqueous solutions… why? (Note: some ionic compounds are too strongly attracted to be soluble in water)
Electrolytes all ionic compounds and some highly polar covalent compounds that can complete an electrical circuit
Types of Electrolytes Strong Electrolytes- inorganic acids, inorganic bases, and ionic compounds that are completely soluble Weak Electrolytes- organic acids, organic bases, ionic compounds that are slightly soluble, and highly polar molecules Nonelectrolytes- nonpolar and organic compounds
Remember? Solutions, Suspensions, and Colloids...
Properties of Solutions rate of dissolving is determined by: agitation, temperature, and particle size Solutions may be unsaturated, saturated, or supersaturated like dissolves like
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