TEST #1January 14, 2014SI sessions- Monday, Tues, Thursday BLOC 105 @ 6PMChapter 1 pages 1-5, 12-25, skim the restChapter 2 pages 31-43Scientific Inquiry- Science- o study of the natural worldo To know nature- Types of biological inquiry:o Discovery of science/inductive reasoning Starts with specific observations and comes to a general explanation for observationso Hypothesis-based science/deductive reasoning- Fig. 1-24 Making Hypothesis- Hypothesis-a tentative answer to a well-framed questiono Testableo Falsifiableo Verifiable- Scientific Theory-broad scope, supported by accumulated evidence from many hypotheses, leadsto new hypotheses, can be modified or rejected- Examples of scientific theorieso Supported: Cell theory Atomic theory Evolutionary theory Chromosomal theoryo Rejected: 5 kingdom theory of biodiversity- Fig. 1-4 levels of biological organization- Chemical Context of life: the foundationo Element My definition-single substance made up of a group of atoms A substance that cannot be broken down to other substances by chemical means 25/92 natural elements are essential for lifeo Molecule My definition-Multiple atoms combined Two or more atoms held together by a chemical bondo Compound My definition- Substance made up of multiple elements and molecules that are chemically combined Two or more different elements held together by chemical bonds, has different properties from elements alone. o Atom Smallest unit having physical and chemical properties of an element Subatomic particlesCharge, mass, location- Protono + , 1 dalton (amu), nucleus - Neutrono Neutral, 1 dalton (amu), nucleus- Electrono -, 0, electron cloud outside of nucleusJanuary 16, 2014It is the number of protons that defi nes the element… if you change the neutrons it changes the isotopePhysical properti es of atoms- Atomic number= number of protons- Mass number/atomic mass= number of protons + neutrons- Isotopes= atoms with more neutronsLook at Figure 2-9 for the physical and chemical properties of atomsExample: Carbon 14- has 6 protons, 8 neutrons and Carbon 12- has 6 protons, 6 neutronsChemical properties of atoms- Electron shells-positions of electrons around nucleus- Valence shell/electrons- outermost; most chemical behavior depends on interactions of these electronsChemical bonds- Covalent-sharing of electrons between two atomso Non polar covalent- electrons shared equallyo Polar covalent- electrons shared unequallyo They are shown in text by a solid line between two elementso ELECTRONEGATIVITY- property of an atom to have a greater attraction to electrons in a bond (within a covalent bond and are USUALLY in the upper right corner of the periodic table of elements ex. Carbon, nitrogen, oxygen, etc) ….. atoms with a high electronegativity pull/attract the electrons towards it.. - Ionic- electrons are transferred from one atom to another due to electronegativity; creates ions…. No sharing AT ALL. (Ex. Chlorine STRIPS/STEALS sodium of an electron to become sodium chloride… ) o Don’t play a huge role in biological reaction EXCEPT for proteins…- Hydrogen bond- weak intermolecular forces that involve attractions between + and – poles (example: between an H atom and an electronegative atom such as O, N, S, or P)o Van der waals forces/ interactionso Shown in text by a dotted line Look at Figure 2-16 for the difference between the two bonds of Hydrogen and Nitrogen. One is covalent and one is a hydrogen bond!!!! CHEMICAL REACTIONS- making and/or breaking chemical bonds leading to production of new compoundsEx: C6H12O6 + 6O2 6H20 +6CO2Identify: reactants: C6H12O6, 602Products: 6H20, 6CO2 Elements: C,H,O molecules: they are molecules because they are all two or more atoms bonded together (even 602 bc it is more than one oxygen bonded together compounds: all except 602 are compoundsCHAPTER 3Read pages 46-56 for chapter 3 and pages 58-66 for chapter 4 Why is water important to life/biology?- Without water there would be no life as we know it today. - (usually) 90% of cells are water- Approx. 75% of the planet is water- Water is important to moderate temperature because water molecuels can absorb a lot of heat…the hydrogen bonds that hold water together… take a lot of input of heat to break the hydrogen bonds even though those bonds are very weak- In the winter: the temperature is warmer by lakes… bc the lakes hold the heat from the summer. How does the chemical structure of water explain:- Cohesion: that why any water molecules sticks to itself… this happens because the formation of hydrogen bonds.- Adhesion: water sticks to other things because it is polar…- High specific heat: it takes a lot of heat to break the hydrogen bonds between water molecules so it can hold and absorb and let off a lot of heat. - Floating ice: hydrogen bonds continue to form in a lattice like structure (making it less dense than water) water expands when forming ice because the molecules don’t move quite as fast so once a hydrogen bond forms…. They will stay longer so the water molecules are forced apart making it 1. Expand and 2. Less dense than water- Hydrophilic interactions: they are able to form hydrogen bonds with water… attracted to water and water wants to interact with them… so a shell of water is formed around them. Life is an aqueous solution- Most biological chemistry involves solutes dissolved in water- Need to calculate concentrations- Molecular mass=measurement of mass of all ATOMS in a molecule…o Example: NaCl= 23 + 35 = 58 daltons- Terms for solute concentrations in aqueous solution:o Molarity (M) = moles of solute/litero Mole = 6.02 x 10^23 objects or Daltons/gram [similar concept= dozen = 12 objects (SOOO the molar mass of 1 mol NaCl is 58 g! TEST YOUR UNDERSTANDING1. What is the number of atoms present in:12.01 grams of carbon: 6.02 X 10 ^23 atoms!! (1 mole)1.008 grams of hydrogen: 6.02 X 10 ^23 atoms!! (1 mole)32.04 grams of sulfur: 6.02 X 10 ^23 atoms!! (1 mole)2. Make a 1 M solution of NaCl1 M= 1 mol NaCl/1 L water… Notes on PH an Buffers- Water can dissociate into IONS:o 2H20 H3O + OHo OR H20 H + OH- Acid- any substance that increases the [H+] in solutiono Donate H+ in aqueous solutions- Base- any substance that decreases the [H+] in solutiono Donate OH- or accept H+ in aqueous solutionsBehavior of acids and bases in aqueous
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