Do Now:

1. Do Now: • Please write down the question. • If you place a water bottle in the freezer, after five hours where would the warmest portion of the water be? • Answer: • The bottom, reason is that water freezes from the top down, so the bottom would freeze last which means it is slightly warmer than the rest of the water bottle.

2. Quick Review • What type of bond: • Answer – Ionic – meaning it transfers electrons

3. Quick Review • What type of bond: • Answer – Covalent – meaning it shares electrons

4. Section 2.2 • Why is water important to determining whether a planet can support life? • Think about Primordial Soup theory. • In our world, 2/3 of the planet is covered with water. Only 2.5 % of all that water is considered fresh water, meaning safe to drink.

5. Section 2.2 • Polarity – Oxygen has 8 electrons, protons and neutrons. Because Oxygen has 8 the otter shell wants to fill in with 2 more electrons which is why it readily accepts 2 Hydrogen molecules to form water. Each element gets what it wants, full otter shells. • Water has a partial negative charge because of the extra electrons. • Polar means the charges are unevenly distributed.

6. Section 2.2 • Hydrogen bonding – The partial negative charge of a water molecule is attracted to a partially positive charged molecule. • These are not as strong as covalent or ionic bonds. • This makes water very unique • It expands when it freezes even though it is more dense when in liquid form.

7. Section 2.2 • Cohesion – attraction between elements of the same substance • Water has high cohesion. Some insects can walk on water. Also, why jumping off a height into the water can feel like hitting cement. • This is called surface tension • Adhesion - attraction between elements of different substances

8. Section 2.2 • Adhesion - attraction between elements of different substances. • Water to glass • Capillary action – when you have blood drawn for donation. When the nurse takes your blood for testing, the nurse uses small glass capillary to draw it up the tube. Same occurs with water.

9. Section 2.2 • Heating water – heat causes the molecules to move faster and cause the temperature to rise. Water’s heat capacity is very high. • At the beach on even a very hot day, the water temperature is not much different from late spring even though it could be mid-summer.

10. Section 2.2 • Mixture – is two or more elements or compounds that are physically mixed together, but not chemically combined. • The atmosphere is a mixture – Oxygen, carbon-dioxide, nitrogen,…. • Two types of mixtures with water – Suspensions and solutions

11. Section 2.2 • Two types of mixtures with water – Suspensions and solutions. • Solution – evenly distributed throughout the solution. Saltwater Solution – salt is the solute – what is dissolved • Water would be the solvent – what dissolves the solute. • If too much solute the solution can be oversaturated. Think about too much sugar in a drink. The sugar cannot be absorbed and chunks of sugar will be found at the bottom.

12. Section 2.2 • Acids, bases and PH

13. Section 2.2 • Why is water neutral / buffer? • Because in water the number of positive ions equals the number of negative ions. • PH scale based on the concentration of Positive Ions (H+). Ranging from 0 to 14, with water being 7 – neutral • Solutions less than 7 are acids • Solutions higher than 7 are basic