BIO1201Noteswap1

BIO1201Noteswap1 - 1/15/09 Exotherms Endotherms Halophiles...

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1/15/09 Exotherms Endotherms Halophiles “love”: High salt Number=Valence Type=Electronegativity Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons Measure of the attraction an atom has Chemical Bond: Forces holding atoms together in molecules Characterized by strong or weak depending on the energy required to make/break the bond Strong o Covalent bonds involve sharing of electrons Weak o Non Covalent bonds Ionic Interactions: Attraction of opposite charges. One atom donates an electron to another. Hydrogen bond: B/t partially charged atoms Valence Vs. Valence Electrons o Valence is the number of electrons needed to fill the outermost shell of an atom o Valence Electrons are the electrons contained in the outermost electron shell of an atom Moles and Molar Concentrations o 1 mole= the mass of a substance equal to its gram molecular weight o 1 molar solution= a solution containing 1 mole of a substance per 1 liter of solution Ionic bonds o Weak bonds o Transfer Covalent Bonds o Strong bonds o Sharing of electrons to complete the valence shell Polar bond
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o Unequal sharing of electrons o Partial + and partial – regions o No net charge Hydrogen bonds o Weak (non covalent) bonds o Between partial pos and partial neg charges Water o 70% to 90% of weight of most life forms o Sets the lower temp limit for life o Sets the upper temp limit? (prob not) o Important part in structure and properties of biological molecules o Water is a biological molecule The unusual properties of water o Results from hydrogen bonding o Water behaves as a much larger molecule Bonds o Covalent H-O 110 k cal per mol o Weak (hydrogen bond): 4.5 k cal/mol H bonding effectively makes water a larger molecule In ice a water molecule interacts with exactly 4 other water molecules In liquid water on avg 3.6 or fewer other molecules (can be made and broken very quickly) Small molecules- a comparison of properties o Water Boiling point 100 C melting 0 C o Ammonia Boiling point 35 C melting -77 C o Ethanol Boiling point 78.5 C melting -117.3 C Unusual properties of water o High heat capacity o High heat vaporization o High heat of fusion o Most dense at 4 C o High dielectric o Capillary action and surface tension o Ionization Heat capacity: Amount of heat to raise temp of 1g of water by 1 C o 1 cal per gram of water
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Heat of vaporization: Amount of heat to vaporize 1 g of water o 540 cal per gram at 100 C Heat of fusion: Amount of heat removed to freeze 1 g of water o 80 cal per gram Water most dense at 4 C because the hydrogen bonding structure ice is lighter than water o Lakes do not freeze from the bottom up High Dielectric: Good solvent
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1/20/09 Capillary Ionization o Dissociation into acid (hydronium ion) Most aquatic animals are ectotherms because of waters high heat capacity Acids, Bases and Salts
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This note was uploaded on 08/22/2010 for the course BIOL 1201 taught by Professor Wishtichusen during the Spring '07 term at LSU.

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BIO1201Noteswap1 - 1/15/09 Exotherms Endotherms Halophiles...

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