Biology 1020-Week 2 class notes and textbook notes for Chapter 3-Dr. Sundermann
Biology 1020-Week 2 class notes and textbook notes for Chapter 3-Dr. Sundermann Biol 1020 - 001 (BIOL, Christine A. Sunderman, Principles of Biology (1020))
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This 10 page Class Notes was uploaded by Laura Notetaker on Wednesday August 31, 2016. The Class Notes belongs to Biol 1020 - 001 (BIOL, Christine A. Sunderman, Principles of Biology (1020)) at Auburn University taught by Christine A. Sunderman in Winter 2016. Since its upload, it has received 61 views. For similar materials see Principles of Biology 1020-001 in Biology at Auburn University.
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Date Created: 08/31/16
Chapter 3 Textbook Notes for Biology 1020 th All notes taken from Campbell Biology 10 Edition by Campbell and Reese Water is the only common substance to exist in the natural environment in all three physical states of matter Concept 3.1: Polar covalent bonds in water molecules result in hydrogen bonding o Polar covalent bonds: when the electrons of a covalent bond between two atoms send more time closer to the more electronegative atom (ex. When oxygen and hydrogen are covalently bonded, the electrons will spend more time around the oxygen because it is more electronegative than the hydrogen) o Polar molecule: the overall charge of the molecule is unevenly distributed; unequal sharing of electrons and water’s Vlike shape make it a polar molecule Concept 3.2: Four emergent properties of water contribute to Earth’s suitability for life Cohesion of Water Molecules: o Cohesion: the hydrogen bonds of water are holding the substance together; ex. water bonds to water o Adhesion: the clinging of one substance to another; ex. Water bonds to other polar and ionic molecules o Surface tension: a measure of how difficult it is to stretch or break the surface of a liquid Moderation of Temperature by Water: Temperature and Heat: o Kinetic Energy: the energy of motion o Thermal Energy: the kinetic energy associated with the random movement of atoms or molecules o Temperature: a measure of energy that represents the average kinetic energy of the molecules in a body of matter, regardless of volume, whereas the total thermal energy depends in part on the matter’s volume o Heat: thermal energy in transfer from one body of matter to another o Calorie: the amount of heat it takes to raise the temperature of 1 g of water by 1 degree Celsius; it is a convenient unit of heat o Kilocalorie: is the quantity of heat required to raise the temperature of 1 kilogram of water by 1 degree Celsius Water’s High Specific Heat: o Specific heat: the amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1 degree Celsius o Specific heat can be thought of as a measure of how well a substance resists changing its temperature when it absorbs or releases heat o Water resists changing its temperature o When it does change its temperature, it absorbs or loses a relatively large quantity of heat for each degree of change o Heat must be absorbed in order to break hydrogen bonds o Heat is released when hydrogen bonds form Evaporative Cooling: o Heat of vaporization: the quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state o To evaporate 1 g of water at 25 degrees Celsius—about 560 calories of heat is needed o Water’s high heat of vaporization is another emergent property resulting from the strength of its hydrogen bonds, which must be broken before the molecules can exit from the liquid in the form of water vapor o Evaporative Cooling: when the molecules with the greatest kinetic energy leaves the liquid as a gas; as a liquid evaporates, the surface of the liquid that remains behind cools down Floatation of Ice on Liquid Water: o Water is one of the few substances that are less dense as a solid than as a liquid o At 0ºC, the molecules become locked into a crystalline lattice, each water molecule become hydrogenbonded to four other water molecules o The hydrogen bonds keep the molecules at “arm’s length”, meaning they are far enough apart from each other to make the ice about 10% dense than liquid water at 4ºC o When ice absorbs enough heat for its temperature to rise above 0ºC, hydrogen bonds between molecules are disrupted o As the crystal collapses, the ice melts and the molecules are free to slip closer together therefore taking the form of liquid water o Water reaches its greatest density at 4ºC Water: The Solvent of Life: o Solution: a liquid that is a completely homogeneous mixture of two or more substances o Solvent: the dissolving agent of a solution o Solute: the substance that is dissolved o Aqueous solution: one in which the solute is dissolved in water meaning that water is the solvent o Hydration Shell: the sphere of water molecules around each dissolved ion o The hydration shell forms when water molecules surround each individual ion—separating and shielding them from each other (ex. Sodium and Chloride ions Na and Cl ) Hydrophilic and Hydrophobic Substances: o Hydrophilic: any substance that has an affinity for water o Hydrophobic: substances that are nonionic and nonpolar (meaning they cannot form hydrogen bonds) repel water Solute Concentration in Aqueous Solutions: o Molecular Mass: the sum of the masses of all the atoms in a molecule 23 o Mole (mol): represents the exact number of objects: 6.02 x 10 also known as Avogadro’s number o Molarity: the number of moles of solute per liter of solution; this unit of concentration is most often used by biologists for aqueous solutions Concept 3.3: Acidic and basic conditions affect living organisms: + o Hydrogen ion: a single proton with a charge of 1+ H o Hydroxide ion: the water molecule that lost a proton therefore has a charge of 1 OH + o Hydronium ion: the proton binds to the other water molecule making the molecule H O 3 Acids and Bases: + o when acids dissolve in water, they donate additional H to the solution o Acid: a substance that increases the hydrogen ion concentration of a solution Ex. HCl H and Cl + + o This source of H results in an acidic solution which means there are more hydrogen ions ( H ) than hydroxide ions ( OH ) o Base: A substance that reduces the hydrogen ion concentration of a solution o Some bases reduce the hydrogen ion concentration directly by accepting hydrogen ions Ex. NH + H + NH + 3 4 o Solutions with a higher concentration of OH than H are known as basic solutions o Solutions with a higher concentration of H than OH are known as acidic solutions o Solutions with the same concentrations of H and OH are known as neutral solutions The pH scale: o [ H ][OH]= 10 14 o An acid not only adds hydrogen ions to a solution but also removes hydroxide ions because of the + tendency for H to combine with OH forming water o A base increases the OH concentration but also reduces the H concentration by the formation of water o The pH of a solution is defined as the negative logarithm of the hydrogen ion concentration pH= log[ H ] o A pH value less than 7 denotes an acidic solution and a pH above 7 denotes a basic solution o A pH value of 7 denotes a neutral solution Buffers: o The presence of substances called buffers allows biological fluids to maintain a relatively constant pH despite the addition of acids or bases o Buffer: a substance that minimizes changes in the concentrations of H and OH in a solution Acidification: A Threat to Water Quality: o Ocean acidification: when an ocean’s pH is lowered; ex. When CO dissolves in seawat2r, it reacts with water to form carbonic acid therefore lowering the pH of the ocean
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