1. Ch 2-2: Properties of Water

2. The Water Molecule: How many Protons? 10 (positively charged)
How many Electrons?
10 (negatively charged)
What is the charge?
(because =0)

3. A. Polarity: Draw a water molecule:

4. Draw Hydrogen bonds between one water molecule and another:

5. 8
1. Oxygen has ___Protons, while Hydrogen only has __ Proton. Oxygen’s greater attraction for electrons causes the Oxygen to have a slightly _____________ charge, while Hydrogen maintains a slightly ___________ charge. 1
Negative
Positive

6. KEY:
A water molecule is polar because:
Polar means ‘uneven charge’. Water is unevenly charged because the Hydrogen atoms are more positive. This is because Hydrogen’s electrons move to the Oxygen (which is then more negative)

7. B. Hydrogen Bonds:
In terms of a water molecule explain what a hydrogen bond is:
The attraction of the positively charged Hydrogen molecule of one water molecule to the negatively charged Oxygen of another water molecule.

8. Cohesion is the ability for water molecules to stick to themselves
Water: Cohesion
Cohesion is the ability for water molecules to stick to themselves
Surface Tension
Beads of Water

9. Cohesion is the ability for water molecules to stick to themselves
Water: Cohesion
Cohesion is the ability for water molecules to stick to themselves
a. How does cohesion explain why some insects can walk on water
Surface Tension
The water molecules are sticking to each other to form a ‘skin’ on the water. The insect is so light, it is not enough force to break the bonds between water molecules.

10. Water: Adhesion
Adhesion is the ability for water molecules to stick to other materials

11. Meniscus in a graduated cylinder
Water: Adhesion
Adhesion is the ability for water molecules to stick to other materials
Meniscus in a graduated cylinder
Water is attracted to the sides of the graduated cylinder- causing the upward curve of the water.

12. b. Capillary action in plants?
Water clings to the inside of plants roots and climbs, just like water will climb up a paper towel if you put half of it in water.

13. Solutions and Suspensions: A. Mixture:
A combination of two or more substances that are physically mixed
They are not chemically combined!!
Examples: soil, salsa, trail mix, milk & cereal, sugar water.

14. Types of Mixtures:
1. Solution: A mixture formed when one substance dissolves in another- molecules are evenly distributed.
Example: Salt Water

15. Parts of a Solution :
a. Solute: the substance that is dissolved in a solution
b. Solvent: the substance that does the dissolving.

16. 2. Suspension: Examples: Blood, Milk, O.J.
Mixture of water and non-dissolved materials
Examples: Blood, Milk, O.J.

17. Drawing of Cohesion: Fresh Water
When water has little or no solutes dissolved in it, water makes lots of H Bonds with itself. This maintains surface tension.

18. Drawing of Cohesion: Salt Water
When water has solutes dissolved in it, water makes H Bonds with solutes to cause them to dissolve. This decreases surface tension.