Ch. 3-1
Water

Polarity
	Hydrogen end is slightly positive
	Oxygen end is slightly negative
	Not arranged in a straight line
	Effective in dissolving substances
	Universal Solvent
	Ionic compound disassociates into ions in water
		NaCl is necessary in many biological reactions
Hydrogen Bonding
	aka molecule bonding
	Water is attracted to itself
	Dissolves ionic compounds very 
	Hydrogen Bond
		Very weak
		Easily broken
		Causes water to cling to itself
		Causes every property of water
		Dissolves ionic compounds very quickly b/c both have charges
Cohesion
	Attractive force between the same kind of polar molecules
	Surface tension of water
		Water has one of the highest surface tensions
		Top layer forms a distinct surface
		Allows water striders not to sink
	Allows water to get to plants
Adhesion
	Attractive force between a polar molecule and another molecule
	Along with cohesion causes:
		Capillarity
			moving up of water through narrow tubes against gravity
				i.e. plant stems
		Meniscus
Temperature moderation
	Water must gain or lose a relatively large amount of energy for its temperature to change
	When heated-most thermal energy is first used to break hydrogen bonds
	When water freezes
		0-4°C water expands
	In organisms:
		water absorbs large amounts of energy
		keeps cells at an even temperature
	Life on earth began in water





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