1. Define electronegativity. How is electronegativity related to polarity? 2. How would you classify water – ionic or covalent bond?

Do Now10 minutes ACT Style Passage10 minutes Water = Life25 minutes Independent Practice15 minutes Exit Ticket5 minutes

Do Now10 minutes ACT Style Passage10 minutes Water = Life25 minutes Independent Practice15 minutes Exit Ticket5 minutes

 Explain how water works in biological systems  Describe the structure and function of water, focusing on polarity  Explain how solubility works with polarity

Water is the solvent of life

as a solid as a liquid as a gas

In a water molecule, the oxygen is more electronegative than hydrogen partial negative partial positive Oxygen pulls the shared electrons toward itself

 It has a positive end and a negative end.  This is called polar (like a magnet). O HH

 Water looks like this: O HH Partial NEGATIVE (-) charge Partial POSITIVE (+) charge

 Remember that ionic bonds are between metals (+) and nonmetals (-)  Because an ionic compound has a positive and negative end, it is also considered a polar molecule.

 NaCl looks like this: Partial POSITIVE (+) charge Partial NEGATIVE (-) charge Na Cl

 Polar substances will dissolve other polar molecules (sugar + water)  Nonpolar substances will dissolve other Nonpolar molecules (gasoline + oil)  Polar + nonpolar substances will not dissolve (water + oil)

 What physical and chemical properties of the liquid can you determine?  What physical and chemical properties of the Styrofoam can you determine?  What conclusions can we draw about the polarity Styrofoam from this demonstration? Defend your answer!

Hydrogen atoms in one polar covalent molecule are attracted to an electronegative atom in another polar molecule

Water molecules stick together due to hydrogen bonding

CAUSES surface tension

Adhesion: Water molecules stick to other things

Adhesion: Water molecules stick to other things

 Honest Abe Challenge...  What chemical properties of water allow this to be possible?

Why does peanut butter help get it out?

Do Now10 minutes ACT Style Passage10 minutes Water = Life25 minutes Independent Practice15 minutes Exit Ticket5 minutes

Read the Article “Freshwater Crisis” and write a one page response: Why is our world in a water crisis if 70% of the world is water?

1. Styrofoam cup dissolving in acetone but not water? 2. Water on a penny? 3. Gum in hair?

1. Draw the structure of a water molecule. Be sure to include the appropriate charges. 2. What property or properties determine whether a substance can be dissolved by water? Give an example in your explanation. 3. Explain how an ionic solid can be dissolved by water.