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Ch.3 The Chemistry of Life

Ch.3 The Chemistry of Life. 1. In a water molecule, how is the charge distributed? a. negatively on the hydrogen side and positively on the oxygen side b. positively on the hydrogen side and negatively on the oxygen side

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Ch.3 The Chemistry of Life

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  1. Ch.3 The Chemistry of Life

  2. 1. In a water molecule, how is the charge distributed? a. negatively on the hydrogen side and positively on the oxygen side b. positively on the hydrogen side and negatively on the oxygen side c. Neither of the above; water is nonpolar and has an evenly distributed charge. 2. How is water's high heat of vaporization beneficial to us? a. It allows us to cool by sweating b. It allows better temperature control inside cells c. It keeps cells from becoming hydrophobic d. It protects enzymes from rises in temperature which would deactivate them 3. The most common two elements in living things are _________ and __________. 4. What characteristic of water allows it to have unique thermal, cohesive, and solvent properties?

  3. Elements found in living organisms: • The most frequently occurring elements in living things are: • Carbon (19%) • Oxygen (65%) • Hydrogen (10%) • Nitrogen (3%)

  4. Other elements needed by living things:

  5. Water Molecule • The two hydrogen atoms bond covalently with the oxygen atom; this creates polarity • Hydrogen side is slightly positively charged while oxygen side is slightly negatively charged

  6. Properties of Water • Because of water’s polarity, water molecules interact with each other in interesting ways • Some properties of water include • Thermal properties • Cohesive properties • Solvent properties

  7. Thermal Properties • High Specific Heat – water can absorb or give off a great deal of heat without big temperature change • This is important for living organisms b/c blood (which is mainly water and therefore stable in temperature) can carry heat to our extremities when cold

  8. Thermal Properties • High Heat of Vaporization – water absorbs a lot of heat when it evaporates • This is important for living organisms b/c they can use it as a cooling mechanism when internal heat results in perspiration, then perspiration evaporates by using your body’s heat which cools you down

  9. Cohesive Properties • Water is cohesive meaning the molecules stick to each other • This is important for living organisms b/c it allows plants to pull water up from their roots against gravity and for animals it allows some insects to ‘walk on water’

  10. Solvent Properties • Water is the Universal Solvent b/c it is polar and therefore other polar molecules like carbs, proteins, and DNA can dissolve in it • This is important for living organisms b/c water is the medium for metabolic reactions

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