Lecture4_2011.keyr

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Unformatted text preview: http://scrippseducation.ucsd.edu/faculty/driscoll/water Chemistry of water Atoms - protons, neutrons, electrons Bonding Hydrogen bond Polar molecule Hydration Big Bang Origin of the Universe Life Cycle of a Star The mass of new matter again collapsed into a disk shape mass of dust and gas (a). The center became superheated and formed a new star, our sun (b). From this disk of matter the planets began to condense (c), according to the widely supported nebular hypothesis of Immanuel Kant and Pierre-Simon Laplace. The two strongest points in favor of this idea are: 1) that the disk began by rotating in one direction and the rotation of all of the planets around the sun follows the original disk; and 2) that because the disk flattened out as time progresses, all of the orbits of the planets (except Pluto) lie more or less in the same plane (d). Pluto is possibly a captured giant asteroid. Origin of our Solar System Atmospheric Evolution • primordial gases, later lost from sun's radiation 2. exhalations from the molten surface (volcanic venting); bombardment from icy comets 3. steady additions of carbon dioxide, water vapor, carbon monoxide, nitrogen, hydrogen, hydrogen chloride, ammonia, and methane from volcanic activity 4. addition of oxygen by plant/bacterial life Water vapor may also be very important Atomic Structure Atomic Structure Helium Neon Krypton Argon Xenon Ionic. Ionic compounds are formed by the transfer of electrons. Elements with 1,2 or 3 outer electrons generally donate the electrons to other atom that is configured to accept them. In the formation of sodium chloride, for example, sodium gives up its outermost electron and becomes a positively charged ion, while chlorine takes on the electron and acquires a single negative charge: Na + Cl --> Na+ClThe transfer of electrons results in an electrostatic force that binds the ions together to form the crystal of sodium chloride. Halogens - red; Alkali Metals - purple Outer shell is called the Valence Shell and filled with Valence electrons Ionic covalent Covalent. Covalent compounds are formed by sharing of electrons rather than an actual transfer. Covalence accounts for the bonding of non-ionic compounds such as: H2 Cl2 CH2=CH2 CH=CH A special type of covalent bond called a coordinate covalent bond or dative bond results when both of the electrons of the bond are supplied by one of the atoms. For example, the production of ammonium ion: NH3 Relative Bond Strength ______________________________________________ Covalent bond (between atoms) Ionic bond (between atoms) usually > 1000 100 Van der Waals force (between molecules) 1 Hydrogen bond 10 Heat Capacity - higher than solid or liquid other than Ammonia - special hydrogen bond • moderates climate • transports large amonts of heat http://scrippseducation.ucsd.edu/faculty/driscoll/water "What makes the planets perfectly spherical?" "What makes the planets perfectly spherical?" A sphere maximizes the volume to surface area "What makes the planets perfectly spherical?" "Is it possible that improvement in water conservation and quality will help to alleviate problems in third-world countries (i.e. water cleanliness), and what effect do you think this would this have on the US?" http://gypsyclicks.blogspot.com/ Latent Heat of Fusion (solid/liquid transition at 0˚C) - higher than any other substance other than ammonia • Add 80 calories per gram to go from ice to water, likewise remove 80 per gram to go from water to ice • when ice forms most of the energy lost is released to the atmosphere; ice absorbs large amounts of heat in melting. Keeps high-latitude water and atmosphere near freezing point all year! Coriolis Force is an ‘Apparent Force’ Latent Heat of Vaporization (liquid/gas transition 100˚C) higher than that of any other substance! 540 calories per gram • regulates temperature of earth and living things - low latitude heat is transported to higher latitudes, http://scrippseducation.ucsd.edu/faculty/driscoll/water Cristo Redentor on Corcovado Mtn http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml Thermal Expansion - pure water has a maximum density at 4˚C, the temperature at which maximum density occurs decreases as salinity increases. • no maximum for salinity above >24.7 (ocean salinites are ~33 o/oo) • Freshwater and low salinity water remains unfrozen under ice Solvent Property - water can dissolve more substances than any other liquid (hydration) • weathering and salinity of oceans • medium for chemical reactions that control life Surface Tension - higher than any other liquid • controls the formation of droplets in atmosphere What is the shape of a rain drop? • bubbles in water Physical States - only substance present as a gas, liquid, and solid within the temperature range at the earth’s surface • moderates climate, changes albedo • if no hydrogen bonds water would freeze at -90˚C and boil at -70˚C and all water on Earth would be gaseous Continental Rocks and Soils are constantly being weathered by water and the salts are transported to the oceans. However, it is thought that the concentration and composition of dissolved salts in the oceans has remained essentially unchanged for millions of years! How is this possible? ...
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This note was uploaded on 03/23/2012 for the course SIO 35 taught by Professor Driscoll,n during the Winter '08 term at UCSD.

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