1. Bellwork Fri. Aug. 28, 2015 Chloride ion Calcium ion Chloride ion
Sea salt contains calcium chloride (CaCl2), an ionic compound similar to table salt. One atom of calcium (atomic number 20) bonds to two atoms of chlorine (atomic number 17). Fill in and draw the number of protons and electrons in each ion.
Chloride ion Calcium ion Chloride ion
Protons ___ Protons Protons___
Electrons ___ Electrons Electrons ___
2. What is the difference between an ionic bond and a covalent bond?
Careful: look at the (-) and (++) 17 20 17 18 18 18
Ionic bonds: transfer of electrons from one atom to another
Covalent bond: share electrons between atoms

2. 2-2 Properties of Water

3. Properties of Water that make Life on Earth Possible……

4. Polarity:
a water molecule is polar because there is an uneven distribution of electrons between oxygen and hydrogen atoms.

5. Hydrogen likes to give electrons away
Oxygen is an “electron hog” – it tugs on electrons so that there is a higher density of electrons around the oxygen as compared to the hydrogen. And
Hydrogen likes
to give
electrons
away

6. 2. Hydrogen Bonds
Because of their partial positive and negative charges, polar molecules can attract each other.

8. 3. Cohesion: an attraction between molecules of the same substance
3. Cohesion: an attraction between molecules of the same substance. Because of hydrogen bonding, water is extremely cohesive.

9. Adhesion:
an attraction between molecules of different substances.

10. 5. Ice floats
in liquid water – water expands when it freezes and is less dense than its liquid form… good news for fish and all aquatic life!

11. 6. High Specific Heat and has ability to remain a liquid over a large temperature range
Why is this important?
(Specific heat is just a fancy way of saying the amount of energy needed to raise the temperature of a substance) sooo… water heats up and cools down slowly….
And… since cells are mostly water – we don’t immediately boil in the desert

12. ….or instantly freeze in the arctic!!

13. 7. Water is the “Greatest Solvent on Earth” A. K. A
7. Water is the “Greatest Solvent on Earth” A.K.A. “the universal solvent” (dissolves stuff) due to its polar nature. - - Important to living organisms because many biochemical reactions take place only within aqueous (water is the solvent) solutions

14. A mixture is a material composed of two or more elements or compounds that are physically mixed together, but not chemically combined

15. Two types of mixtures can be made with water solutions and suspensions

16. Suspensions 
Some materials do not dissolve when placed in water but separate into pieces so small that they do not settle out easily. Blood is about 55-60% water

17. Solution: components are evenly distributed throughout the solution
Solution: components are evenly distributed throughout the solution. When a crystal of table salt is placed in warm water, sodium and chloride ions are attracted to the polar water molecules.
When an ionic compound such as sodium chloride is placed in water, water molecules surround and separate the positive and negative ions.

18. salt in salt water. solute: the substance that is dissolved. Like the
solvent: the substance in which the solute dissolves. Like the water in salt water.

19. Acids, Bases, and pH
A water molecule is neutral, but can react to form hydrogen (H+) and hydroxide (OH-) ions.
H2O   H+ + OH-

20. The pH scale 
indicates the concentration or [ ] of H+ ions in solution.
The pH scale ranges from 0 to 14.

21. The pH Scale
At a pH of 7, the concentration [ ] of H+ ions = OH- ions, so the solution is Neutral
The concentration of H+ ions determines whether solutions are acidic or basic.

22. Acids
An acid is any compound that forms H+ ions in solution. 
HCl = Hydrochloric acid –
Stomach acid

23. Bases It is slippery to the Feel – like bleach
A base is a compound that produces hydroxide ions (OH- ions) in solution. 
It is slippery to the
Feel – like bleach

24. Buffers: weak acids or bases that can react with strong acids/bases to prevent sudden changes in pH
The pH of the fluids within most cells in the human body must generally be kept between 6.5 and 7.5.
Controlling pH
is important for
maintaining
homeostasis.

27. The 2 chemical bonds in water:
Bellwork: Wed. Sept. 3, 2014
The 2 chemical bonds in water:
covalent bonds between the oxygen and the hydrogen atoms result from a sharing of the electrons. This is what holds the water molecules themselves together.
hydrogen bond is the chemical bond between the water molecules that holds the mass of molecules together. A drop of falling water is a group of water molecules held together by the hydrogen bonds between the molecules.

30. 2-2 Section Review Quiz
A molecule in which the charges are unevenly distributed is called a
polar molecule.
cohesive molecule.
hydrogen molecule.
covalent molecule.

31. 2-2 A dissolved substance is called a solvent. solution. solute.
Suspension.

32. 2-2
A compound that produces hydroxide ions in solution is called a(an)
base.
buffer.
acid.
salt.

33. 2-2 Hydrogen bonds between water molecules result from
adhesion between water molecules.
magnetic attractions between water molecules.
uneven electron distribution in each water molecule.
ionic bonds in the water molecule.

34. 2-2 On a pH scale, a value of 2 means that the solution has
equal concentrations of H+ and OH- ions.
the same concentration of H+ ions as pure water.
higher concentration of H+ than in pure water.
lower concentration of H+ than in pure water.

35. The END

36. Bellwork Tues. Sept. 2, 2014 Cl - - has _____electrons.
2. Magnesium has an atomic mass of?_______
and this one has ____electrons
______, _______ and _________ are the 3 most common elements in your body.
What atom is this?_____________

37. 5. The 4 most common elements in your body:1 2 3 4