Biology 1201: Unit 1Chapters 1-5Check Moodle for videos & homeworkGreen = DefinitionsBlue = ListsOrange = Questions Asked in ClassI. Introduction:a. What is Science?A study of the natural world to acquire a body of knowledgeA way of understanding the natural worldIt is a process (input) to a body of knowledge (output)b. What do scientists do?Make observationsMake modelsMake predictions/hypothesesDiscern PatternsAssume that the future is like the pastc. Scientific Method:What are the basic steps of the method?Observations Generalization or Model Predictions or Hypothesis TestWhat is the outcome of this process?Make new observationsFind more informationCreate better modelsTerminology:Hypothesis – A prediction or explanation for a phenomenon that is untested, it is a statementTheory – an explanation or prediction for something that has been tested many times and is supported, believed to be accurateLaw – a theory that has been continuously tested, widely believed by scientists, closest to reality (most tested)What is Biology? The scientific study of lifeWhat is life? It is made up of many characteristicsWhat are the characteristics of life? (Underlined words will be covered in class)OrganizationUse energyAdapt/Respond to environmentGrowth and developmentReproduceEvolveMade up of cellsIt is important to realize that each characteristic by itself cannot support life. Living things must have ALL of these characteristics to be considered living things.Example: Viruses do not have all these characteristics, so they aren’t alive, Antibiotics kill bacterial infections and cannot kill virusesWhat determines solubility?Like dissolves likeCompounds which are similar dissolve one anotherLike in terms of polarityPolar solutes dissolve in polar solventsNonpolar solutes dissolve in nonpolar solventsExample: nonpolar molecules can enter through the cell membrane, but polar molecules cannotWhat determines polarity?The type of bonds within a moleculeThe sharing of electrons determines polarityII. Basic Chemistry:Scale of Nature: What are the sizes of biologically important structures?Solubility: like dissolves likeAtoms:Smallest units of matter that are separable by normal chemical meansSmallest unit of an element that retains all the elements propertiesComposed of many smaller particlesAtomic Structure:ParticleMassElectric ChargeLocationProton1 Dalton+NucleusNeutron1 Dalton=NucleusElectron0 Daltons-Outside of CellElectrons DO have mass, but it is very smallElectrons make up the volume of an atom and protons & neutrons make up the massValence: (Bonding capacity)The number of electrons that need to be gained or lost to fill the outer shell of electronsAlso predicts the number of bonds that an atom will formThey will want to gain or lose the SMALLER numberValence electrons: (chemistry)The electrons in the outermost shellQuestions:Lithium has the atomic number of 3. What is the valence of Li?1Carbon has the atomic number 6. What is the valence?4Bohr Model:This model has electrons moving in orbitals or shells around the nucleus. The electrons always try to be in the lowest orbital or energy shell (that is closest to the nucleus)The Lowest Level = KThe Next level = LThe Third Level = MAn atom is most stable when the outer most shell of electrons was fullQuestions:Oxygen has the atomic number 8. What is its valence (bonding capacity)?22K – 6LEasier for it to gain 2 than lose 6Phosphorus has the atomic number 15. What is the valence (bonding capacity)?2 K – 8 L – 5 MEasier for it to gain 3 than lose 5Atoms will try to gain or lose electrons in order to fill their outer shell or valence shell. The number of electrons to be gained or lost is called the valence.Chemical Bonds:Form when atoms gain and lose or share electronsThey are the result of electrical attractions between atomsIonic Bonds:Form when atoms completely gain and lose electronsStrongest bonds when dryCovalent Bonds:Form when atoms share electronsIf shared equally – then they are nonpolar covalentIf shared unequally polar covalentStrongest bonds in waterClicker Questions:Are Covalent, Polar Covalent, and Ionic Bonds really different bonds?They are similar except for the degree of sharing of electronsWhat determines the number and type of chemical bonds?Number = determined by the valenceType = determined by ElectronegativityElectronegativity:The measure of the tendency of an atom to attract a bonding pair of electronsMeasure of the attraction an atom has for electronsIf it wants to gain an electron HIGHIf it wants to lose an electron LOWAs you go from left to right across the periods of the periodic table, the electronegativity increasesThe electronegativity of the Nobles Gases is ZEROThe electronegativity also increases as you go up a groupElectronegativity and Bonds:Ionicwhen differences are 1.7 or greater, the bond is usually ionicCovalent (non-polar)when differences of less than 0.5Polar Covalentwhen the difference is greater than 0.5 and less than 1.7, it is a polar covalent bondClicker Questions:The Carbon-Carbon bond is which type of bond (electronegativity)?Covalent because the electronegativity is 2.5; 2.5-2.5 = 0, 0 is less than 0.5 which corresponds to a Nonpolar Covalent BondThe Carbon – Oxygen bond is which type of bond?Polar Covalent because the electronegativity is 3.5-2.5 = 1.0, between 0.5 & 1.7 which corresponds to a polar covalent bondThe Na-Cl bond is which type of bond?Ionic because the electronegativity is 3.0-0.9 = 2.1, greater than 1.7 which corresponds to an ionic bondThe C-H bond is which type of bond?Covalent because 2.5-2.1 =0.4, less than 0.5 which corresponds to a nonpolar covalent bondHow do bonds influence the polarity of a molecule?Molecules which contain a majority of ionic bonds will be polarMolecules which contain a majority of polar covalent bonds will be polar (with some exceptions)Molecules which contain a majority of pure covalent bonds will be non-polarStrong Bonds:Bonds which are the result of very strong electrical attractions, where electrons are lost or gained are called Ionic BondsBonds which are the result of electrical attractions which are not so strong, where the electrons are shared are covalent bondsWeak Bonds:Bonds which are not involved in making a substanceHydrogen Bonds:Weak electrical attractions between atoms on different molecules or different parts of a large
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