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Materials for Life

Materials for Life. NBSP Physical Science Leadership Institute. Professor Lynn Cominsky Joanne del Corral Sharon Janulaw Michelle Curtis July 9, 2003. Standard Connections.

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Materials for Life

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  1. Materials for Life NBSP Physical Science Leadership Institute Professor Lynn Cominsky Joanne del Corral Sharon Janulaw Michelle Curtis July 9, 2003

  2. Standard Connections • Students know properties of solid, liquid and gaseous substances, such as sugar (C6H12O6), helium (He), and Oxygen (O2), nitrogen (N2) (5) • Students know the common properties of salts, such as sodium chloride (NaCl) (5) Prof. Lynn Cominsky

  3. First Activity: Sugar and Salt • How are sugar and salt different? • If we couldn’t taste them, how could we tell which is which? Prof. Lynn Cominsky

  4. Sugar and salt investigations: • Given: quantities of sugar & salt, and all the equipment that you have been using during the past two weeks • Can you predict how the physical properties of sugar and salt might differ? • Can you design experiments to differentiate between sugar and salt? Prof. Lynn Cominsky

  5. Key concepts about Sugar • Sugar is a type of carbohydrate and the most common molecules found in plants and animals • Carbohydrates are literally Carbon that is hydrated  Carbon + water • C6H12O6 is glucose • Other common sugars: • sucrose C12H22O11 • fructose C6H12O6 • All sugar names end in “ose” as do other carbohydrates Prof. Lynn Cominsky

  6. Structure of Glucose Prof. Lynn Cominsky

  7. Key concepts about Salt • In its simplest form, Salt is a molecule that pairs one element from the first group in the periodic table (e.g., Na) with an element from the seventh group (e.g., Cl) • Group 1 elements have one unpaired electron in their outer shells, while Group 7 elements are missing an electron to complete their outer shells Prof. Lynn Cominsky

  8. Key concepts about Salt • Salts can be formed by mixing an acid and a base to form a salt and water • For example: Hydrochloric acid + Sodium Hydroxide table salt + water HCl + NaOH  NaCl + H2O • In solutions, salt dissociates into Na+ and Cl- ions • Na+ has lost one electron • Cl- has gained one electron • Ionic solutions can conduct current Prof. Lynn Cominsky

  9. Structure of NaCl Prof. Lynn Cominsky

  10. Second activity: Comparing gases • Helium, Nitrogen and Oxygen are all commonly occurring gases • Consult the periodic table to compare the properties of these gases • Can you draw pictures of the structure of each gas? • Consult the materials in your binder to compare the uses of these gases Prof. Lynn Cominsky

  11. Key concepts: Common gases • Helium is a Noble gas – it is the second most common element in the Universe but is only present in trace amounts in the Earth’s atmosphere • Nitrogen and Oxygen are diatomic gases which are rare in the Universe but • 78% of the atmospheric volume is nitrogen • 21% of the atmospheric volume is oxygen • They are both very chemically reactive Prof. Lynn Cominsky

  12. Structure of Common Gases:N2 • Nitrogen gas is a diatomic molecule formed from two atoms of Nitrogen. • Each atom has 7 electrons. • The inner shell is filled with 2 of these electrons, leaving a total of 5 electrons that try to fill the next shell (which holds 8) for each atom. • A triple covalent bond between the two nuclei shares 3 pairs of the electrons. • Two other electrons are individually bonded to each nucleus. Prof. Lynn Cominsky

  13. Structure of Common Gases:O2 • Oxygen gas is a diatomic molecule formed from two atoms of Oxygen. • Each atom has 8 electrons. • The inner shell is filled with 2 of these electrons, leaving a total of 6 electrons that try to fill the next shell (which holds 8) for each atom. • A double covalent bond between the two nuclei shares 2 pairs of the electrons. • Four other electrons are individually bonded to each nucleus. Prof. Lynn Cominsky

  14. Vocabulary • Salt: ionic molecule that pairs a group 1 and a group 7 element • Sugar: molecule that combines Carbon with an integral number of water molecules • Ion: elemental form with extra or missing electrons • Noble gas: an element in Group 8, which has a filled outer shell and is chemically (rather) inert Prof. Lynn Cominsky

  15. ELD Activities: Visual Imagery • Make a slide show, or have images ready to show to the students. • Ask them to first write down on a piece of paper or in their journal whether the object shown is a liquid, a solid, or a gas. • Then ask volunteers to give their answer. Prof. Lynn Cominsky

  16. Publisher’s Materials • Take some time to look through the state-adopted texts to find activities relating to commonly occurring substances, such as sugar, salt and atmospheric gases Prof. Lynn Cominsky

  17. Break – something to think about • Why do you think the relative abundances of helium vs. nitrogen/oxygen are so different between the Universe and the Earth’s atmosphere? Prof. Lynn Cominsky

  18. Standard Connections • Students know atoms and molecules form solids by building up repeated patterns, such as the crystal structure of NaCl or long-chain polymers. (8) Prof. Lynn Cominsky

  19. Third Activity: Structure of Solids • Given: toothpicks, styrofoam balls • Use the toothpicks to represent electrons in the outer shells • Use the styrofoam balls to represent the nuclei of the various elements • Create models for NaCl, Glucose, Nitrogen gas and oxygen gas • Compare the models – what are the structural differences between Sugar and Salt? Between N2 and O2? Prof. Lynn Cominsky

  20. Key concepts: Structure of Sugars • Sugars come in many forms • Monosaccharides – glucose, fructose • Disaccharides - sucrose • Polysaccharides – made of many smaller glucose type rings • Polysaccharides include starch, glycogen and cellulose Prof. Lynn Cominsky

  21. Structure of Solids: Polymeric Molecules • Starch is made of many units of glucose • Numbered corners are C-H (not shown) • This is (a small part of) amylose  4000 units of glucose Prof. Lynn Cominsky

  22. Further investigations: Slime! • Given: Borax, white glue, water, food coloring, ziploc bag • Add 1 Tbsp. Borax to 1 cup water, stir until dissolved • Make a solution of ¼ cup water and ¼ cup glue – mix thoroughly • In a ziploc bag, add equal parts borax solution and glue solution • Add a couple of drops of food coloring • Seal bag and knead mixture • Dig in and have fun! Prof. Lynn Cominsky

  23. Further questions: • What are the properties of slime? • How can we tell that this is a polymer? • What other polymers do you know? Prof. Lynn Cominsky

  24. Key concepts: Structure • Ionic crystals such as salt, have a regular lattice structure • Repeating units in salt are cubic in shape – the molecule is also cubic • Sugars have units that can repeat to make complex carbohydrates such as starch • Repeating units are cyclic in shape – the overall molecule is chain-like Prof. Lynn Cominsky

  25. Vocabulary • Polymer – complex molecule made of repeating units in a chain-like structure • Crystal – molecular structure made of repeating units in a cubic structure • Saccharide – sweet substance • Starch – polysaccharide that is used for energy storage in plants • Glycogen – polysaccharide that is used for energy storage in animals Prof. Lynn Cominsky

  26. ELD Activities: Analogies and Student Involvement • Have the students investigate their favorite food and snacks. • Ask them to look at the “Ingredient List” on the label of the food packaging and list all the words ending in “ose” in their journal. • Go over the words with them the next day. (A hint on health awareness might be welcome there as well!) Prof. Lynn Cominsky

  27. Publisher’s Materials • Take some time to look through the state-adopted texts to find activities relating to structure of common molecules • Examples: MH p. 221 Prof. Lynn Cominsky

  28. Lunch – some things to think about How do sugars and starches provide energy for plants and animals? Prof. Lynn Cominsky

  29. Standard Connections • Students know how to determine whether a solution is acidic, basic or neutral (8) Prof. Lynn Cominsky

  30. Fourth Activity: Cabbage Juice Science • Make your own acid/base indicator by boiling red cabbage. • Use the juice to test whether different fluids are acids or bases. • Compare the pH results from the cabbage juice to those obtained using litmus paper. Prof. Lynn Cominsky

  31. Equipment for Cabbage Juice activity • red cabbage juice • vinegar and lemon juice • baking soda, powdered lime, and liquid soap • some plastic spoons, stirring sticks, and 4 plastic cups • 5 medicine droppers • 1 marker Prof. Lynn Cominsky

  32. Cabbage Juice Activity: • Label 6 clear plastic cups with numbers 1-6 • Fill all cups up ~1/4 of the way with cabbage juice. • Collect your five samples • Vinegar • Lemon juice • Baking soda • Powdered lime • Liquid soap (non-antibacterial) • Place a small amount of each sample into each of five of the plastic cups. • If your sample is an acid, it will turn the cabbage juice pink. If your sample is a base, it will turn the cabbage juice green. Prof. Lynn Cominsky

  33. Further investigations: • Label 2 clear plastic cups: 1 and 2 • Fill all cups up ~1/4 of the way with water. • Place one known acid and one known base into each of the cups. • Place a piece of litmus paper into each of the cups. • Basic solutions will turn red litmus paper blue and will leave blue litmus paper unaffected. • Acidic solutions will turn blue litmus paper red and will leave red litmus paper unaffected. Prof. Lynn Cominsky

  34. Key concepts: pH • Acidic solutions contain an excess of protons or H+. pH is a measure of how 'acidic' a solution is. The lower the pH, the more acidic the solution. • In chemical terms, pH means "the negative log of the concentration of protons" in solution. Chemistry students should recognize this as pH = -log[H+]. Prof. Lynn Cominsky

  35. Key concepts: pH • "Neutral" solutions (e.g.,water) have a pH of 7. This number coincides with the amount of H+ naturally formed in water from the equilibrium reaction: H2O  H+ + OH- • "Basic" solutions have a pH greater than 7, meaning that they have less free H+ than that in neutral water. Prof. Lynn Cominsky

  36. Key concepts: pH • Red cabbage contains pigments call anthocyanins. The pigments give it the red/purplish color. Anthocyanins belong to group of chemical compounds called flavonoids. • Other plants that contain anthocyanins include beets, cranberries and blueberries. Prof. Lynn Cominsky

  37. Vocabulary • pH: A measure of the acidity or alkalinity of a solution, numerically equal to 7 for neutral solutions. The pH scale commonly in use ranges from 0 to 14. • Base: Any of a class of compounds whose aqueous solutions are characterized by a bitter taste, a slippery feel, the ability to turn litmus blue, and the ability to react with acids to form salts. • Acid: Any of a class of substances whose aqueous solutions are characterized by a sour taste, the ability to turn blue litmus red, and the ability to react with bases and certain metals to form salts. Prof. Lynn Cominsky

  38. ELD Activities: Visual imagery and student involvement • Form groups of 14 students. • Have all students wear an “H+ sign”. • Draw a circular boundary (one per group) on the ground and ask each group to make “acidic, neutral, or basic solutions” by adding, or removing “H+s (represented by each student) using the pH scale as a reference. Prof. Lynn Cominsky

  39. Publisher’s Materials • Take some time to look through the state-adopted texts to find activities relating to pH, acids and bases. • Examples: HM p. C78 Prof. Lynn Cominsky

  40. Break – some things to think about • Do you think pH would be a useful test to discriminate between sugar and salt? • Why or why not? Prof. Lynn Cominsky

  41. Standard Connections • Students know living organisms and most materials are composed of just a few elements (5) Prof. Lynn Cominsky

  42. Fifth Activity: Essential elements in living organisms • Review the handout in the binder that includes many tables summarizing the elemental abundances in different locations • How many elements are essential to plants? To animals? • How do the abundances change from the Universe to the solar system? Prof. Lynn Cominsky

  43. Fifth Activity: Essential elements in living organisms • How do the abundances change from the solar system to the atmosphere? • How do the abundances change from the atmosphere to the oceans? • How do the abundances change from the oceans to the crust? • How do the abundances change from the crust to plants? Prof. Lynn Cominsky

  44. Further investigations: • What do these changes tell you about the evolution of life in the Universe? Prof. Lynn Cominsky

  45. Key concepts: Essential Elements • Light elements (H and He) dominate the early Universe • As the solar system formed, heavier elements (made in stars) were incorporated to make the planets • The atmosphere is about ¾ N2 and ¼ O2 • There are a limited number of elements that are essential to plants and animal life, including H, C, N and O. Prof. Lynn Cominsky

  46. Vocabulary • Abundance: relative amount of an element Prof. Lynn Cominsky

  47. ELD Activities: Compare and Contrast Table A Prof. Lynn Cominsky

  48. ELD Activities: Compare and Contrast Table B Prof. Lynn Cominsky

  49. Questions for ELD Tables: 1. Using table A and B, list the common elements you see in living organisms and materials: 2. What does this tell you about living organisms and most materials? Are they similar in any ways? Prof. Lynn Cominsky

  50. Publisher’s Materials • Take some time to look through the state-adopted texts to find activities relating to the elements that are essential to plants and animals Prof. Lynn Cominsky

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