Do now….

1. Do now…. • Three things that you know about water.

2. Properties of Water Why it is so special

3. But first….. • Some continuation/review of what we know • Molecule • Compound • Element • Proton • Neutron • Electron

4. what am I? • I am an element that has different forms with different numbers of sntopro. • Example: Helium

5. Bonds • Ionic: Bonds formed where one atom takes an electron from another atom. • Example: Salt (NaCl) • Covalent: Bonds formed when electrons are shared between atoms. Example • Chlorine gas (Cl2) • Water (H20)

6. Formation of Sodium Ion Sodium atom Sodium ion Na  – e Na + 2-8-1 2-8 ( = Ne) 11 p+ 11 p+ 11 e- 10 e- 01+

7. Formation of Magnesium Ion Magnesium atom Magnesium ion  Mg  – 2e Mg2+ 2-8-2 2-8 (=Ne) 12 p+ 12 p+ 12 e- 10 e- 0 2+

8. Some Typical Ions with Positive Charges (Cations) Group 1 Group 2 Group 13 H+ Mg2+ Al3+ Li+ Ca2+ Na+ Sr2+ K+ Ba2+

9. Finally….water!

10. The Structure of Water

11. The Polarity of Water • Water is polar. This means that some parts of it are positively charged, and some are negatively charged. • This means that different water molecules can be attracted to each other.

12. Hydrogen Bonds • This is when molecules of water bond to each other because of the positive and negative charges being attracted to each other. • These connections last for only fractions of a second and rapidly form and break. Hydrogen Bonds Movie

13. Hydrogen Bonds in Water

14. This also creates water tension • What is it? • It is what allows some insects and lizards to “walk on water”. (Think the itsy bitsy spider song) Jesus Lizard 1Jesus Lizard 2Jesus Lizard 3Jesus Lizard 4

15. Cohesion • Cohesion- Attraction between molecules of the samesubstance. • Hydrogen Bonding demonstrates this well.

16. Penny Fun! • Fill your cup to the brim with water. • How many pennies can you get into the cup before it overflows! • Can you see the water above the brim of the cup? • Number of pennies _______________ • Try it 3 times. • Now try a paper clip. Can you get it to float?

17. Adhesion • Adhesion-The attraction between molecules of different substances. • A Meniscus in a graduated cylinder • Plants pulling water up through their roots. • A good way to remember: ADhesion is ADDITION to a different substance.

18. So….. • Is water tension cohesion or adhesion?

19. Solutions • A solution is a mixture which includes water. • Components are evenly distributed • Solute- What is dissolved. • Solvent- What the solute is dissolved in. • Example: Saltwater: • Salt is the solute • Water is the solvent

20. Water as a Solvent • Water is a great solvent because of its’ polarity (only with polar and ionic molecules). • Why is it a great solvent with polar molecules? • Why is it a great solvent with ionic molecules?

21. Suspensions • A suspension is similar to a solution EXCEPT the solute does not dissolve. • However the solute is in small enough groupings to be suspended in the water. • Blood • Muddy water

22. Solution Suspension

23. Phases It exists in three phases in natural environments. Ice Water Gas (Steam)

24. Ice, Ice, Baby! • Ice forms when water freezes. • When this happens, hydrogen bonds become locked in place. During this the space between molecules increases. • This is “weird” because with most liquids, the molecules are closer together than with solids. • Since the ice is less dense than water, it floats!

26. Floating Ice • Since ice floats, it stays ON TOP of the water. • Ice on top of lakes helps to insulate them (keep them warmer) during the summer. • If ice sank, it would go to the bottom of the ocean and never melt….eventually most of the ocean would just be one block of ice. (And earth might be colder.)

27. We All Need It! • It is needed to live by all life on earth for most body processes. • Also, a large part of all organisms on earth is composed of water.

28. Water as Solvent Most solutions have water as their solvent. Think of your favorite drink. ______________ Does it have water in it? YES/NO What are clouds made of? What is milk made of? What is blood made of?

29. Cohesion and Adhesion Water’s cohesion and adhesion properties allow it to be found in many places on earth and used by many organisms.

30. How plants get their water • Adhesion or cohesion?

31. How water can be sucked up in a straw • Adhesion or Cohesion?

32. Why water stays in drops (instead of flattening out) Adhesion or cohesion?

33. Its high heat of vaporization. This means that it takes lots of heat to change water from a liquid to a gas. (Vaporization) (This is why the evaporation of sweat cools us off). • Think of how much heat it takes to boil water! 100 degrees Celsius or 212 degrees Celsius. That’s HOT!

34. High-Specific Heat • Water’s high-specific heat. • This means that water can release or take in a large amount of heat without more than a slight change in temperature. • How a pothandle can be hot even if the water is only warm. • Think of the biosphere (earth), the oceans keep the earth’s temperature relatively stable (think of other planets).

35. Closing Questions • What is one reason that water is important on earth? • Why does ice float? • Draw the structure of water. • What is the difference between adhesion and cohesion. Please give an example of each.