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Notes Week 4 Biology

Notes Week 4 Biology. During the video…. What is polarity? Which element attracts more than their fair share of electrons? Why? What does covalent mean? What atoms are covalently bonded? Why are the hydrogen and oxygen attracted to each other?

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Notes Week 4 Biology

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  1. Notes Week 4 Biology

  2. During the video… • What is polarity? • Which element attracts more than their fair share of electrons? Why? • What does covalent mean? What atoms are covalently bonded? • Why are the hydrogen and oxygen attracted to each other? • What is water’s ability to stick to other objects called?

  3. During the video… • What is polarity? THE UNEQUAL SHARING OF ELECTRONS • Which element attracts more than their fair share of electrons? Why? OXYGEN, IT IS BIGGER AND HAS MORE PROTONS • What does covalent mean? SHARING OF ELECTRONS • Why are the hydrogen and oxygen attracted to each other? OPPOSITES ATTRACT • What is water’s ability to stick to other objects? ADHESION

  4. COLLEGE READY! Note Structure Solutions Definition: a. Solute b. Solvent c. Insoluble Example:

  5. Solutions

  6. What is a Solution? Definition: A solution is a mixture of one or more substances dissolved in another substance. A solution is composed of a solute and a solvent.

  7. SOLUTE A. Solute. A Solute is a substance dissolved in a liquid to form a solution. For example: Coffee Oxygen Sugar

  8. SOLVENT B. Solvent. A Solvent is a liquid that takes into itself a solute (which can be in the state of a solid, liquid or gas) and creates a solution.For example:

  9. Sugar Solution Sugar Water Mixture Solute Solvent Solution

  10. Do all substances dissolve in a solvent?

  11. C. Insoluble. Some substances are unable to dissolve in a solvent such as sand, chalk and oil. These are said to be insoluble.

  12. COLLEGE READY! Note Structure Water • General Information • Polarity • Forces • Hydrogen Bonding • Cohesion • Adhesion • Properties • Capillary Action • Surface Tension

  13. Terms to Know polarity hydrogen bond cohesion adhesion surface tension capillary action Specific heat Solute solvent

  14. Water I. GENERAL INFORMATION Most abundant naturally occurring liquid Liquid at most Earth temperatures Unlike most liquids – it expands when frozen The lower density of ice allows it to float (4°C most dense)

  15. Water H2O II. POLARITY • Water is neutral • But because the O atom is larger than the H atoms – electrons spend more of their time nearer the oxygen • This gives water a slight overall charge • That charge is called polarity

  16. 1. Forces due to polarity • Hydrogen Bonding • Cohesion • Adhesion

  17. A. Hydrogen Bonding • Polarity really does allow bonding • They are hydrogen bonds and they are very weak • They last for fractions of a second • Continuously break and reform • Polarity allows for hydrogen bonding (weak) • They last for fractions of a second • Continuously break and reform

  18. Hydrogen Bonding • http://www.slideshare.net/aszz/hbonds

  19. The natural attraction of a water molecule to other water molecules B.Cohesion

  20. Example: Can be seen as water droplets form

  21. The attraction of a water molecule to another polar molecule Molecules such as soil and clay (dust) Surfaces like glass or paper straws Certain clothing fibers and … animal hair C. Adhesion

  22. Example Can be seen as water droplets form on the spider web (another polar surface)

  23. Two simple 2. properties associated with polarity are A. Capillary Action B. Surface Tension

  24. A. Capillary Action • We know that gravity is ALWAYS pulling on objects with mass • Yet water can move up a paper towel with relative ease - How can this happen? • Because the positive and negative charges in the paper attract the polar water molecules (adhesion) allowing water to defy gravity and climb. • This property of adhesion is called capillary action

  25. EXAMPLE:

  26. B. Surface Tension Inside a drop of water polar water molecules attract to each other in a random fashion At the surface of the drop, water does not attract to the air A unified layer of molecules at the surface creates surface tension There the water behaves like an flexible sheet allowing denser objects to “sit” on the surface

  27. EXAMPLE:

  28. Review Forces Forces Properties Polarity hydrogen bonding cohesion adhesion surface tension capillary action

  29. STATIONS You will get a packet with 6 assignments. When it says “*See Supplement” You will have to flip to the back of this packet. You MUST bring this packet to class EVERYDAY until it is completed. It is VERY IMPORTANT. Today we will complete part 1. GRADING SHEETS.

  30. Water Density

  31. The density of water is very special compared to other types of liquids.

  32. Words to know Expand means to get bigger Contract means to get smaller Density is how close or far apart the molecules in a substance are

  33. Cooling things down... Often when substances are cooled down, they contract and become more dense. Often when substances are heated, they expand and become less dense. Mainly when substances are cooled, they contract and become more dense, such as metal. Pretend that if got colder and our room was to shrink a lot. We would all be forced to move closer together, making it more dense.

  34. Railroad Tracks When the winter weather comes around and the temperature dips, metal contracts and becomes more dense. When it is summer and the temperature rises, the metal expands and becomes less dense. That is why there are spaces between the tracks so the metal can expand in the summer.

  35. Is this true for ice cubes?

  36. No, it is not. We know this because when we put an ice cube into water it floats! This lets us know the ice cube is less dense than the liquid water. When water is ice it expands, therefore less dense.

  37. EXAMPLE This is key to many animals and plants surviving in the winter. When a pond freezes, it freezes on the top.

  38. This allows the plants on the bottom to still have oxygen, and the animals, such as fish that live in the water, can still eat those plants. If the ice was more dense than liquid water, ice would sink to the bottom of the pond and kill everything.

  39. But Hold On! Please do not get confused, just because ice cubes are less dense than liquid water does not mean that cold water is less dense than hot water. Cold water is more dense, so when mixed with hot water, the hot water will float on top. There will be a video to show you this.

  40. DURING THE VIDEO Which is more dense, freshwater or saltwater? Why do you think there are different lines on the Titanic for Freshwater and Saltwater? Why are there different lines for winter water and summer water?

  41. Watch this video http://www.youtube.com/watch?v=Ak9CBB1bTcc

  42. STATION 2

  43. FUN VIDEO Watch this one if you finish early http://www.youtube.com/watch?v=GYoJiMtn_Xc&feature=fvsr

  44. Have you ever noticed that on a hot summer day the pool is cooler than the hot cement? OR maybe that the ocean is cooler than the hot sand?

  45. Specific Heat Capacity Specific Heat: The amount of heat required to raise the temperature of 1 gram of a substance 1 degree Celsius. • 1 calorie = 4.184 J 1,000 J = 1 KJ 4,184 J = 1 Kcal = 1 Calorie

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