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Next Time – pp. 50 -71

Next Time – pp. 50 -71. First … scale. http://www.powersof10.com/film. http://www.loc.gov/exhibits/eames/science.html. Chemistry. Elements – substances that can’t be broken down into other things See the periodic table Look at all those elements Only the first 94 occur naturally

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Next Time – pp. 50 -71

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  1. Next Time – pp. 50 -71

  2. First … scale http://www.powersof10.com/film http://www.loc.gov/exhibits/eames/science.html

  3. Chemistry • Elements – substances that can’t be broken down into other things • See the periodic table • Look at all those elements • Only the first 94 occur naturally • Life is mostly CHON - remember those letters

  4. Atoms • Atoms – the smallest units of elements. EVERYTHING IS MADE OF ATOMS • Atoms are made of protons, neutrons, and electrons • +, x, and - charges

  5. Atoms • Mostly the same number of each of these in each atom • Deviations from this give us radioactive isotopes (different # neutrons) • Number of protons determines identity • Different numbers of these make atoms of different elements • Number of electrons determine how atoms will bond together • Into molecules

  6. Different arrangements of the same atoms can give different substances http://focus.aps.org/story/v22/st5

  7. Bonding • There are three major types of bond between atoms • Covalent, ionic, and hydrogen (also Van Der Waals) • Strongest to weakest in that order

  8. Bonding • Covalent = shared electrons • Ionic = donated electrons • Hydrogen = magnetic attraction between polar molecules • Electrons determine how many and how strong the bonds are

  9. Shape! • Molecule shape determines how it interacts with other molecules • Like our smell receptors • Like neurotransmitters in your brain • Like the nicotine in tobacco killing the insects that eat it

  10. Water • Hydrogen bonding – cohesive qualities of water • Very important • What causes it: • negative charge on O, positive on H+ • Many effects…

  11. Surface Tension http://www.freefoto.com/preview/16-31-23/Raindrops http://gallery.hd.org/_c/natural-science/_more2006/_more01/meniscus-on-water-surface-tension-supporting-steel-paperclip-in-drinking-glass-tumbler-beaker-5-AJHD.jpg.html http://alphavilleherald.com/2007/03/surface_tension.html http://www.flickr.com/photos/cdm/53197139/

  12. Frozen water floats My picture

  13. Cohesion • Trees can suck water up to 379.1 feet! http://redwoods.info/showrecord.asp?id=3248

  14. Specific Heat • Moderates climate & body temperature (we’re more than 50% water) http://www.worldmapsonline.com/SatPosters/WashingtonStateSpace.htm

  15. Good Solvent • Because of its strong polarity • Dissolves many substances (the universal solvent) • Good medium for chemical reactions (us)

  16. Acids and Bases • Low numbers = acidic = high [H+] • High numbers = basic = high [OH-] • Neutral = 7 http://www.bcscience.com/bc10/pgs/quiz_section5.1.htm

  17. Acids and Bases • Effects of strong acids and bases • Acids can corrode metal • Destroy flesh - burn • Bases also eat your flesh - soap

  18. Buffers • It’s a combination of chemicals • Releases OH- in the presence of acids • Releases H+ in the presence of bases

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