AP Biology Chapter 3 Guided Reading Assignment – Flashcards
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Why is water considered a polar molecule?
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The electrons in a water molecule are shared unevenly- oxygen is highly electronegative, so it pulls electrons toward it (unbalanced = polar)
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What is cohesion, and how does it relate to water?
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Cohesion: The property of like molecules sticking together (positive attracts negative- hydrogen bonds hold the substance together) In water: Because the hydrogen unbalances the molecule, hydrogen bonds are created and holds the molecules together.
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What is an example of cohesion in nature?
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Water molecules in the xylem of a tree- the water resists gravity and moves up the xylem in the trunk.
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What is adhesion, and how does it relate to water?
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Adhesion: The attractive forces between unlike molecules In water: Because water has both positively and negatively charged ends, it is more attracted to other molecules. The adhesion of water to cell walls by hydrogen bonds counters the downward pull of gravity.
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What is an example of adhesion in nature?
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Water molecules sticking to grass blades and leaves after dew.
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What is surface tension, and how does it relate to water?
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Surface Tension: The tension of the surface film of a liquid caused by the attraction of the particles in the surface layer from the liquid. In water: At the surface of water, a certain arrangement of water molecules (hydrogen bonded to one another) creates a "film" on top of the water.
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What is an example of surface tension in nature?
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Some animals may stand, walk, or run on water because of its great surface tension.
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What is specific heat, and how does it relate to water?
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Specific Heat: The heat required to raise the temperature of 1g of a substance by 1°C In water: Water has a high specific heat due to the many hydrogen bonds needed to make or break depending on the heat energy.
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What is an example of specific heat in nature?
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Specific heat in water helps to regulates the temperature of an area surrounded by large amounts of water.
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What is heat of vaporization, and how does it relate to water?
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Heat of Vaporization: The quantity of heat that must be absorbed if 1g of liquid is vaporized (at a constant temperature) In water: The strong hydrogen bonds in water also cause it to have a high heat of vaporization.
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What is an example of heat of vaporization in nature?
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Water's high heat of vaporization causes steam burns on some organisms (sometimes severe ones).
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What is evaporative cooling, and how does it relate to water?
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Evaporative Cooling: Molecules wit the greatest kinetic energy are most likely to leave as gas In water: Because of the hydrogen bonds in water breaking, some water evaporates. Then, new hydrogen bonds are formed and the surface of the liquid that remains behind cools down.
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What is an example of evaporative cooling in nature?
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Evaporation in plant leaves keeps the tissues in leaves from becoming too warm.
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What is special about water and density?
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When water freezes, it floats, unlike most liquids. This allows life in the liquid below the ice during cold temperatures.
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What is a solute?
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The substance dissolved in a solution.
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What is a solvent?
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The dissolving agent in a solution.
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What does hydrophilic mean?
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Having an affinity (mix, dissolve, or be wetted) to water
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What does hydrophobic mean?
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Repelling water
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What is an acid?
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A liquid that increases the hydrogen ion concentration of a solution (has a pH of less than 7)
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What is a base?
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A liquid that reduces the hydrogen ion concentration of a solution: -Some directly accept hydrogen ions -Others dissocate to form hydroxide ions to form water with oxygen ions.
