Bio 151, Week 2
Bio 151, Week 2 Bio 151
Cal State Fullerton
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This 6 page Class Notes was uploaded by Aimee Dennis on Monday February 8, 2016. The Class Notes belongs to Bio 151 at California State University - Fullerton taught by Alison Miyamoto in Spring 2016. Since its upload, it has received 16 views. For similar materials see Cellular and Molecular Biology in Biology at California State University - Fullerton.
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Date Created: 02/08/16
Week 2 Chemical Foundations: Water & Carbon a. Diagram of atoms Nucleolus Hydrogen Carbon - Proton # = Electron # - Protons + Neutrons = Atomic mass Isotopes: more forms of the same element with the same amount of protons but different amount of neutrons - Elements can have different number of neutrons and become radioactive - Elements are characterized by their proton number - Electrons determine the number of bonds that atoms form - Move in orbitals that hold up to 2 electrons/orbital - Orbitals are grouped into shells that have a characteristic numbers of orbitals Ex: 1 shell holds 2 electrons and all outer shells Orbitals Electrons - The number of unpaired electrons in the outermost shell determines the number of bond that an element can form - Inner shells are filled entirely before outer shells Valence Shell: outer most shell - Unpaired electrons make the atom less stable - Further away the skill is from the nucleus the more reactive the atom - A filled valence shell is the most stable (thermodynamically) - Chemical bond can fill valence shell So how many chemical bonds can be formed for H,C,N,O atoms? 1, 4, 3, 2 Ionic Bonds Loss of an electron ???????? + Na Cation formation Gain of an electron F ???? − Anion formation Ionic bonds: the complete transfer of valence electrons between atoms who share a chemical bond Covalent Bonds H H H H Hydrogen atoms each have Hydrogen molecules have an unpaired electrons two shared electrons (H-H) Three types of covalent bonds: 1) Single bond Ex. H-H 2) Double bond Ex. O=C=O 3) Triple bond Ex. N≡N Covalent bond types: a) Non polar covalent bond in Hydrogen molecule H H Share electrons equally, balanced electronegativity b) Polar covalent bonds in water molecule O H H - Electrons not shared equally, so partial charges exist on the O and H atoms - Electron Continuum: O > N > C ≅ H Where would ???? f2t on the continuum? Nonpolar covalent, same electronegativity as O - Water is a very important molecule for life on Earth - Denser as a liquid than a solid - High specific heat - Solvent for other polar molecules Hydrogen bonds: form between hydrogen atoms with a positive charge and another atom with a negative charge (not in non-polar bonds) - Individual Hydrogen bonds are very weak - Anything that is polar can be solubilized in water Hydrophilic: love of water Hydrophobic: fear of water Which molecule would more easily dissolve in water? Carbohydrate, since water is polar you would need another polar item Valence electrons: the number of electrons in the outermost shell Valence: how many bonds can you form - Water can neutralize strong acids and bases due to its chemical properties Theoretical: ???? ???? ↔ ???? + ???????? − 2 + + − Actual: 3 ???? (ℎ???????????????????????????? ???????????? → ???? ???? +2???? ???? ↔ 2 ???? + ????3 Acid: donates a protein, less than 7 on pH scale Base: accepts a protein, more than 7 on pH scale pH scale: serves as a measure of the concentration of hydrogen ions (proteins) in a solution - The more acidic a solution, the more ???? ions are present -Water is an excellent butter against pH changes Chemical Reactions and their nomenclature Reactant 1 + Reactant 2 -> Product OR Reactant -> Product 1 + Product 2 -The equilibrium state of a reaction depends upon the number of collisions What are the major regulators of chemical reaction? Temperature and concentration o Higher temperature -> more collision -> more product o Higher concentration -> more collision -> more product Chemical evolution: the first step in the development of life on this planet through the oceans of the early history of Earth Importance of Carbon -Most versatile atom on Earth -Carbon can form many covalent bonds -Molecules containing carbon can form almost limitless arrays of shapes Functional Groups - Amino accepts proton (base) - Carboxyl donates a proton (acid) Process: Chemical evolution Hypothesis 1) Simple molecules were present in atmosphere of ancient Earth (temp & conc.) 2) The energy in sunlight drove reactions among the simple molecules 3) Complex molecules formed - Simple -> Complex What happened/ the pattern (Carbon containing molecules) - Energy -> Sunlight and Heat -> chemical process Thermodynamics: the study of energy conversion into work, heat and power -Law of Thermodynamics requires a closed system (e.g universe) Types of energy 1) Potential energy 2) Kinetics energy 3) Other forms of energy st Thermodynamics 1 law - Conservation of energy - Cannot create energy - Cannot destroy energy Second Law of Thermodynamics Entropy: amount of disorder in a group of molecules - Entropy always increases -Chemical reactions result in products with less order -Results in lower potential energy and increased disorder (chemical and physical process) -More order= less entropy Chemical energy: potential energy stored in chemical bond -Covalent bonds store energy -More potential energy in non-polar bonds than polar bonds
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