1. Take packet from front (mark it pg 19 in binder) and on the back … answer the below questions: Draw an atom with its 3 subatomic particles – in correct locations & label List 5 things with water in them Section 2-2 Interest Grabber continued DO NOW

2. What type of water do you drink? 1.Tap 2.Bottled 3.Both

3. Did any list contain any living things? DO NOW Let’s discuss your list … Did your lists contain some of the same things? Did anything on the other list surprise you?

4. I. Facts A. 75% of Earth’s surface is water B. Cells are 70 – 95% water! C. expands when freezes 1. when in solid format is actually less dense than in liquid state Properties of Water

5. II. Water Molecule A. Molecule is neutral 1. has 10 protons and 10 electrons B. Water is a polar molecule 1. water is bent - the O molecule is more negative than the H 2. Therefore water is polar because of the uneven distribution of electrons btwn the O & H atoms a. negative pole is near the O atom & positive pole is btwn the H atoms

6. 3. has special properties a. due to ability to form multiple hydrogen bonds 1 - can be as many as 4 at a time C. Hydrogen bonds 1. Example a. molecules of water & hydrogen are held together by H-bonds 2. can be attracted to each other a. due to having both a partial positive & partial negative 3. not as strong compared to ionic or covalent

7. D. Properties 1. cohesion a. attraction btwn molecules of the same substance b. water extremely cohesive c. water’s cohesion makes the molecules on surface to be drawn inward 1 - reason why water on a smooth surface beads up 2 - also why insects & spiders can walk on water

8. 8 Cohesion Attraction between molecules of same substance b/c of H bonding, H 2 0 extremely cohesive Molecules on surface of H 2 0 drawn inward Beading effect Insects can walk on pond’s surface

9. 2. Adhesion a. attraction btwn molecules of different substances b. Example 1- reading water level in graduated cylinder a - water dips in center b - 2 different molecules (water/glass) c – adhesion btwn water molecules & glass molecules is stronger than the cohesion btwn water molecules

10. 2 – water rises higher agst the force of gravity in a narrow tube a – known as capillary action b – a force that draws water out of the roots of a plant & up the stem & leaves c – cohesion holds the water together as it rises

11. 11 Adhesion Attraction between molecules of different substances Meniscus in graduated cylinder Water climbs slightly up glass, dips in middle Rises against force of gravity, aka: capillary action – H 2 0 out of roots into stems of plant

12. The water molecule’s charge is ____ 1.Positive 2.Negative 3.Neutral Countdown 10

13. The water molecule is an example of _______ 1.Mixture 2.Solution 3.Compound 4.Suspension Countdown 10

14. Cohesive occurs with different molecule substances 1.True 2.False Countdown 10

15. Is water cohesive or adhesive? 1.Cohesive 2.Adhesive Countdown 10

16. When water goes from solid state to a liquid state, molecules ______ 1.Do nothing 2.Expand 3.Contract Countdown 10

17. Is water polar or nonpolar? 1.Polar 2.Nonpolar Countdown 10

18. IV. Solutions & Suspensions A. water not always pure – often found as a mixture 1. mixture – material composed of two or more elements or compounds that are physically mixed together but not chemically a. examples 1 - salt & pepper – mixed but only physically 2 – sugar and sand 3 – earth’s atmospheric gases

19. B.Two types of mixtures can be made with water 1. Solution a. a homogenous mixture of 2 or more substances 1 – substance breaks away then dissolves b. parts of a solution 1 - Solute – substance being dissolved 2 - Solvent – dissolving agent http://www.northland.cc.mn.us/biology/biology1111/ani mations/dissolve.html

20. 2.Suspension a. substance does not dissolve, but breaks into small pieces b. the movement of water molecules keeps the molecules suspended 1 – mixture of liquid & undissolved material c. examples 1- your body (blood, mostly water with other cell types)

21. The water molecule is an example of _______ 1.Mixture 2.Solution 3.Suspension Countdown 10

22. The atmospheric gases on Earth are an example of _____ 1.Mixture 2.Solution Countdown 10

23. Making kool-aid is an example of ____ 1.Mixture 2.Solution Countdown 10

24. V.Acids, bases, & pH A. water can react to form ions 1. ex - forms Hydrogen ions (H + ) & Hydroxide ions (OH - ) 2. how often? a. in pure water 1 in every 550 million

25. B.pH scale 1. used to determine the concentration of H + in a solution 2. ranges from 0 to 14 a. 7 range is neutral b. having a pH below 7, makes it more acidic, ‘cause it has more H + c. having a pH above 7 are called basic, because they have more OH - Neutral Increasingly Basic Increasingly Acidic Oven cleaner Bleach Ammonia solution Soap Sea water Pure water Human blood Milk Normal rainfall Acid rain Tomato juice Lemon juice Stomach acid

26. 3. pure water’s pH scale is 7 4.Strong acids and bases dissociate completely when mixed w/ water

27. C. Acids 1. forms when H + ions are in a compound 2. increases H + conc. (less than 7) 3. strong acids tend to have a pH value btwn 1 – 3 a. example - HCl (stomach acid)

28. D. Bases 1. forms when the compound has OH - ions 2. reduces H + conc. (greater than 7) 3. strong bases tend to range from 11 to 14 a. example - NaOH, lye

29. E.Buffers 1. weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH levels

30. 30 Acids, Bases & pH Buffers help to neutralize the acid or base Examples? – Tums, Rolaids

31. 2. Internal pH of most cells is about 7 a. if changes will affect the chemical reactions that take place there b. changes in pH can be harmful to cells c. important to maintaining homeostasis d. Buffers – minimize changes in concentrations of H + and OH - in a solution – so cells adjust slowly

32. Stomach acid is very acidic 1.True 2.False

33. Buffers are needed to make an acidic a basic 1.True 2.False Countdown 10

34. Is bleach acidic, neutral or basic? 1.Acidic 2.Neutral 3.Basic

35. Is water acidic, neutral or basic? 1.Acidic 2.Neutral 3.Basic

36. Complete review questions