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WKU BIOL 120 - Water and the Chemical building Blocks of Biology (chapter 2 & 3)

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BIOL 120 1st Edition Lecture 4Outline of Last Lecture II. Basic Atomic Structurea. Matter, Element, Atoms, Protons, Neutrons, Electrons, Molecules, Energy, Chemical Energy, Thermodynamics, Atomic Number, Atomic Mass, Isotope, III. Chemical Bondsa. Valence electrons, Valence, Chemical Reaction, Covalent Bond, Ion, Cation, Anion, Ionic Bond IV. Representing Molecules a. Molecular formulas, Structural formulas, Ball and stick models, Space filling models, CPK coloring modelsOutline of Current Lecture II. Watera. Hydrogen bonds, hydrophilic, hydrophobic, cohesion, adhesion III. Reactionsa. Acid, base, salt, buffer, chemical equilibrium, endothermic reaction, exothermic reaction, Redox, oxidation, reduction IV. Energya. Energy, potential energy, kinetic/ thermal energy, heat, first law of thermodynamics, Gibbs free-energy change, exergonic, endergonic V. Some key terms to know a. Solution, solvent, solute, aqueous solution, molecular weight, molarity VI. Chemical Building Blocks (start of chapter 3)a. Organic compound, isomer, structural isomer, stereoisomer, enantiomer Current LectureII. Water 1. It’s single most important chemical property is that it can form hydrogen bondsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.A. This is the weak bond between the partially negative O atoms and partially positive H atoms of two water molecules 2. It is a great solvent A. This is because the covalent bonds in water are polar  can bond to other atoms i. Oxygen has a partial negative charge. a). Valance: 2 (bonds to form)ii. Hydrogen has a partial positive charge.a). Valance: 1 B. Hydrogen bonds: the weak electrical attractions between the partially negative oxygen of one molecule and the partially positive hydrogen of a different water moleculei. can also form between a water molecule and any other polar molecule 3. Water and Hydrogen bondsA. Hydrogen bonds make it possible for almost any polar or charged molecule to dissolve in water i. Hydrophilic: can dissolve; “water loving” i.e. sugara).ii. Hydrophobic: uncharged and nonpolar compounds that repel from water i.e. oil/ fata).4. Structure and Properties of waterA. Unique because: small size, bent shape, highly polar covalent bonds, overall polarity B. Properties:  cell structure and function depend on these**i. Cohesive  binding between like molecules a). due to hydrogen bonds holding the substance together b). it can resist rupturing when stretched  high surface tension 1). i.e. insects or leaves floating on the surface of waterc). This property allows for water to pull up from the roots to stems and leaves1). i.e. First Nutrients that the tree needs dissolve into the water  Cohesion Allows water to overcome gravity transportational pulli). When hot, plants transpiration (loss of water from outer part of the plant (holes in leaves))  causes plants to wilt but cools the temp of the plant due to evaporation of water ii. Adhesive- Binding between unlike molecules iii. Denser as a solid than a liquid  expands as it changes from a liquid to a solid iv. Ability to absorb large amounts of energy a). can do this because it has a high specific heat, high heatof vaporization, and can stabilize its temperature b). Hydrogen bonds allow water to stabilize c). it can absorb or release large amounts of heat with veryslight changes in temperature  this is how water protectscells from their own metabolic heat III. Reactions A. pH1. expresses proton concentration in a solution i. Pure water = 7ii. Acids: < 7a) a substance that increases H concentration in a solution iii. Bases: > 7a). a substance that reduces H concentration of a solution 2. pH scalei. change in one unit of pH = 10X change in H concentrationa). i.e. pH 4  pH 5 = 10Xb). pH 4  pH 6 = 100X ii. Salt: a reaction between an acid and a baseiii. Buffer: a compound that minimizes changes in pH  found in the human body for homeostasis 3. Chemical reactionsi. occur when:a). one substance is combined with another  atoms are rearranged b). one substance is broken down into another  molecules are split into atoms or smaller molecules i.e. aerobic respiration ii. Reactions have reactants and products iii. Chemical equilibrium: occurs when the forward and reverse reactions proceed at the same rate and the quantities of reactants and products remains constant iv. Endothermic reaction: need to absorb heat to reactv. Exothermic reaction: release heat during a reactionvi. Redox: during some chemical reaction, electrons can be transferred from one atom to another while still retaining the energy of their position in the atom a). Oxidation: loss of an electronb). Reduction: gain of an electron vii. Spontaneity of a chemical reaction is deterimined by:a). the amount of potential energyb). the degree of order viii. Temperature and concentration affect reactions a). Higher temperature  more collisions  faster reactionb). Higher concentration  more collisions  faster reactionc). Lower temperature  less collisions  slower reaction d). Lower concentration  less collisions  slower reaction IV. Energy1. What is itA. Energy: the capacity to do work or supply heati. Potential energy: stored energy (an object’s position determines its ability to store energy a). i.e. electrons in the outer shell have more potential energy than electrons in an inner shellii. Kinetic/ thermal energy: the energy of movement that is measured as a temperature2. Heat and First Law of ThermodynamicsA. Heat: the thermal energy transferred between objects of different temperaturesB. First Law of Thermodynamics: energy is conserve  it cannot be created or destroyed, but it can be transferred or transformed i. i.e. photosynthesis  changes light energy into chemical energy 3. Gibbs Free-Energy ChangeA. Gibbs free-energy change (∆G): determines whether a reaction is spontaneous or requires energy i. ∆G < 0  an exergonic spontaneous reaction (releasing energy)ii. ∆G > 0  endergonic reaction (requires energy input)iii. ∆G = 0  a reaction at equilibrium V. Some key terms to know1. Solution: a liquid that is a homogeneous mixture of two or more substances2. Solvent: the dissolving agent of a solution i.e. water3. Solute: the substance that is dissolved i.e. sugar4. Aqueous solution: a solution in which water is a solvent 5. Molecular


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