Be sure to attend lab this week WATER PROPERTIES Bring the lab manual Must pass lab to pass this class Instructors will give percent lab grade to one another Supplemental Textbook Material Ch 16 p 349 361 Covalent Bonds Need octet of electrons surrounding element in the dot diagram Some bonds are multiple stronger Octet Rule for Oxygen Start with dot diagram Don t have octets of electrons Share two pairs to get to eight for each atom Covalent Bond Chlorine Gas Covalent bond Draw dot diagram for each atom Bond using all electrons Octet around each Show bonding pair with a line Naming Compounds Find subscripts to indicate how many of each atom in the molecule Use chart at right for number of each Indicate with double bar 1 Polar molecules Electro negativity Poly atomic ions Common poly atomic ions Covalently bonded compounds Not electrically neutral Maintain covalent bonds within ions as they interact with other ions to form ionic compounds Those bonded to oxygen become ate Hydroxide Bicarbonate Carbonate Sulfate Nitrate Phosphate Chromate Chemical Formulas Molecule has specific ratio of elements Subscripts how many Parentheses how many sets Coefficients how many molecules in reaction OHHCO3CO32SO42NO3PO43CrO42 Chemical Formulas H2SO4 Ca3 PO4 2 Na2O CaCl2 CaO 2 NaCl MgBr2 2Ag NO3 Mg NO3 2 2AgBr 2 Predict Molecule Shape Electro negativity Draw molecule dot diagram Put most electronegative element in the center of molecule Predict Molecule Shape Draw molecule dot diagram Put most electronegative element in the center of molecule Arrange other atoms around it Include all unbonded pairs and bonds so that each atom has octet of electrons Choose tentative shape from number of atoms plus unbonded pairs Geometry of Molecules Predict Molecule Shape Choose tentative shape from number of atoms plus unbonded pairs Erase unbonded pairs Adjust shape to account for the empty spots Tetrahedrons may become pyramids 3 d shapes may become bent Typical Shapes of Molecules 3 Tetrahedral molecules Bent molecules Dipole attraction in solid and liquid Pyramidal molecules Polar molecules Dissolution of ionic substance 4 Solute Solvent Water Molecule Bent Covalent bonds Polar Dissolves ionic substances Distribution Cycle Animation Water phases and molecules Properties of Water Solid water floats on liquid water High specific heat High heat of vaporization Universal solvent Hydrologic Cycle 5 Natural substances in water Impurities in Runoff Organic byproducts in water Atmosphere Dissolved substances Silt etc Radon Contamination of Water Drinking water standards Micro organisms Decay products Plant nutrients Petroleum compounds Acid Industry Mining Be sure to attend lab this week Bring the lab manual Must pass lab to pass this class Instructors will give percent lab grade to one another 6 Water Drop Heat and Energy Transfer Supplementary Textbook Material Chapter 18 p 410 420 Review Questions 2 4 21 26 http www wested org pblnet exp projects H2O html Impurities in Runoff Organic byproducts in water Atmosphere Dissolved substances Silt etc Radon Pollution Sources Contamination of Water Micro organisms Decay products Plant nutrients Petroleum compounds Acid Industry Mining 7 Raw Sewage discharge http www nwri ca sande nov dec 2002 e html Agricultural Runoff Plant nutrient pollution http www na fs fed us SPFO pubs n resource riparianforests Tab 20I htm Oil pollution http www intertanko com tankerfacts sizes pollution htm http www na fs fed us SPFO pubs n resource riparianforests Tab 20I htm Mine leachate Water Pollution http www jvkco com digidare water html http www ew govt nz enviroinfo hscs contam 8 Water Pollution Prevention Drinking water standards http www jvkco com digidare water html Temperature Quantity of hotness Celsius freezing point of pure water at standard pressure 100o boiling point at standard pressure 0o Fahrenheit 0o was lowest attained 32 was his age when he performed experiments 212 is boiling point in those increments Temperature Convert with equations Parentheses first Then multiply or divide Add or subtract last Or use adjacent scales such as in the appendix of Earth Science textbook p 683 Temperature Kelvin same size as degree Celsius Absolute Zero is 0 K notice no degree symbol on K 0o C 273 K Equation for Prelab exercise 2 has error K 273 Co change to 5 C F 32 9 Order of operations 9 F C 32 5 Heat Calorie Amount of heat required to raise the temperature of 1 mL pure water 1o C Food Calories are kilocalories Joule of calorie 1 cal 4 184 J 9 Specific Heat Capacity Quantity of heat needed to change the temperature of given amount of a substance 1o C Water very high specific heat capacity Maritime areas more mild temperature than continental areas Water Expansion Unusual response to cooling Contracts until reaching 4o C Expands slightly upon further cooling to 0o C Expands 9 upon freezing Water Expansion Heat Expansion Random motion causes substance to be bigger Liquids usually have greater heat expansion than solids Thermostats use different expansion of different type of metals Water Molecule Bent Polar Water Expansion Molecule shape fit together closer in liquid Open structured crystal due to hydrogen bonding of polar molecules upon freezing http www elmhurst edu chm vchembook 122densityice html 10 Electron Structure Diagrams Heat of Water Two ways to correctly do these With elemental symbol in center With number of protons in center Supplementary Textbook Materials Chapter 19 Pages 424 435 Not with circles around symbol and electrons distributed around circle Dot Diagrams Phases of Matter Only show VALENCE Electrons Don t show shells Gas Liquid and Solid Solid Liquid Gaseous or vapor Plasma Evaporation Kinetic energy of molecules Taken from liquid cools it Gaseous phase or vapor phase Gas Liquid Solid Zumdahl Zumdahl DeCoste World of Chemistry 2002 page 441 http www unit5 org christjs Matter 20and 20Energy Unit 202 20PP files frame htm 11 Water vapor Gas Steam H2O g Steam http www unit5 org christjs Matter 20and 20Energy Unit 202 20PP files frame htm Evaporation or Not http en wikipedia org wiki Water vapor Condensation Opposite of evaporation Kinetic energy of molecules Heats environment http www geology sdsu edu classes geol351 01watercycle watercyclefigs htm Condensation on Glass Liquid Water H2O l Water http www geology sdsu edu classes geol351 01watercycle watercyclefigs htm http www unit5 org christjs Matter 20and 20Energy Unit 202 20PP files frame htm 12 Atmosphere Evaporation
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