Competency Goal 3 …build an understanding of the hydrosphere. In your text book, on page xxv, copy all of competency goal 3. Copy objectives 3.01 – 3.08

Competency Goal 3 The learner will conduct investigations and utilize appropriate technologies and information systems to build an understanding of the hydrosphere.

Obj Analyze the unique properties of water including: Universal solvent cohesion and adhesion Polarity Density and buoyancy Specific heat Obj Explain the structure of the hydrosphere including: Water distribution on earth Local river basin Local water availability Obj Evaluate evidence that Earth’s oceans are a reservoir of nutrients, minerals, dissolved gases, and life forms: Estuaries Marine ecosystems Upwelling Behavior of gases in the marine env. Value and sustainability of resources Deep ocean technology and understandings gained

Obj Describe how terrestrial and aquatic food webs are interconnected: Obj Analyze hydrospheric data over time to predict the health of a water system including:: Temperature dissolved oxygen pH Nitrates Turbidity Bio-indicators Obj Evaluate technologies and information systems used to monitor the hydrosphere.

Goal 3.07 Describe how humans affect the quality of water: Point and non-point sources of water pollution in NC Possible effects of excess nutrients in NC waters Economic tradeoffs Local water issues Goal 3.08 Recognize that the good health of environments and organisms requires: Monitoring of the hydrosphere Water quality standards Methods of water treatment Maintaining safe water quality Stewardship

& notes Water has polar covalent bonds. That means that the hydrogen atoms and the oxygen atom share electron pairs, but not equally. Oxygen has +8 charge in its nucleus and attracts the electrons to it more frequently than Hydrogen’s +1 charge. This gives the Oxygen part a negative charge and the Hydrogens a positive charge

This polarity will cause the water molecules to shift around so that the “+” and “-” charges balance out. This is easy while water is a liquid, but when it freezes, and the molecules can not continue to shift and float around, they have to spread out to evenly space the “+” and “-” charges. This is why ice expands when it freezes. This is also why ice floats. Solid water has a lower density than liquid water.

Water’s polarity also gives rise to its other unique characteristics. Cohesion – ability to stick to itself. Because of its polarity, the “-” charge on the oxygen is pulled towards the “+” side of other water molecules’ hydrogens. This is why when water is leaking from a faucet, it builds up into a large drop before falling. The water is “holding” onto other water molecules. Adhesion – ability to stick to other things. Water also sticks to other things, because of its polarity. Water droplets stick to the side of a glass, because of their attraction to the molecules in the glass.