Lab 3 Write Up - The Chemistry of Water and Biomolecules PDF

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Laboratory 3: Write Up Assignment I. Chemical Bonds Virtual Lab Procedure: Go to the website http://www.teachchemistry.org/bonding You should see a picture of the Periodic Table on your screen. Part A: Ionic Bonding #1-13 0.5 points each 1. Choose Sodium (Na). What type of element is it and how many valence electrons does it have? Sodium (Na) is a metal type and has one valence electrons 2. Choose Fluorine (F). What type of element is it and how many valence electrons does it have? Fluorine (F) is a nonmetal/halogen and has 7 valence electrons 3. Answer the question on the screen, “What type of bond is this combination likely to form?” Sodium Fluoride (NaF) is likely to form an ionic bond. 4. Choose the appropriate number of atoms to make the bond. Record the number of each atom below: Watch the final animation closely (it will play continuously). Describe the change in the number of valence electrons in the atoms as the bond is successfully formed. Sodium will only nee one atom and fluorine will also only need one atom. When these two elements bond Na donates it’s one electron so that fluorine can have a full valence shell. 5. What does the positive (+) charge indicate (mention specific subatomic particles in your answer)? Sodium had a postive charge because it was the electron donor. 6. What does the negative (-) charge indicate (mention specific subatomic particles in your answer)? Fluorine had a negative charge because it was the electron receiver. 7. What is the final overall charge The overcharge would be neutral. 8. What is the name AND formula for the compound formed? NaF (sodium fluoride) Reset the selected data using the Reset symbol (arrow that looks like an “undo” button) 9. Choose Calcium (Ca). What type of element is it and how many valence electrons does it have? Calcium (Ca) is a metal and has 2 valence electrons. 10. Choose Chlorine (Cl). What type of element is it and how many valence electrons does it have? Chlorine (Cl) is a nonmetal and has 7 valence electrons.

11. Answer the question on the screen, “What type of bond is this combination likely to form?” An ionic bond is likely to form. 12. Choose the appropriate number of atoms to make the bond. Record the number of each atom below: Watch the final animation closely (it will play continuously). Describe the change in the number of valence electrons in the atoms as the bond is successfully formed. Calcium (Ca) will have 1 atom and chlorine (Cl) will have 2 atoms. Calcium lost two electrons and chlorine gained those two 13.What is the final overall charge? What is the name AND formula for the compound formed? The overall charge is neutral. CaCl2 (Calcium Chloride) Reset the selected data using the Reset symbol (arrow that looks like an “undo” button) 14. Using a Periodic Table, complete the chart below. Then, use the simulation to check your answers by clicking on the appropriate elements to make each compound. (2 points, 0.5 points per row) Atom #1

# Valenc e

Charg e

Atom #2

# Valenc e

Charg e

Formu la

Formula Name Sodium oxide

Na

1

1+

O

6

2-

Na2O

K

1

1+

F

7

1-

KF

Mg

2

2+

Cl

7

1-

MgCl2

Ca

2

2+

N

5

3-

Ca3N2

Al

3

3

S

6

2-

Al2S3

Part B: Covalent Bonding #15-22 0.5 points each 15. Now, you will investigate diatomic molecules, those that are made up of two of the same type of atom. Select 2 fluorine atoms. How many valence electrons are in each fluorine atom? There are 7 valence electrons 16. Is a fluorine atom a metal or a non-metal? Nonmetal 17. Did the combination of these atoms create a covalent or ionic bond? Covalent bond

Potassium Fluoride Magnesium chloride Calcium Nitride Aluminum Sulfide

18. How are the valence electrons organized to form a bond between these atoms? How is this different from the ionic bonds formed in the previous part of the activity? The electrons are being shared 19. Select 2 oxygen atoms. How many valence electrons are in each oxygen atom? There are 6 valence electrons. 20. Is an oxygen atom a metal or a non-metal? Nonmetal 21. Did the combination of these atoms create a covalent or ionic bond? How are the valence electrons organized to form a bond between the atoms? Created a covalent bond and they are shared 22. How is this bond different from the bond in the fluorine molecule in question 1? In ionic bonds what we typically see is a donation or transfer of electrons, but when covalent bonds are formed they share their electrons II. Properties of Water Virtual Lab #23-27 1 point each 23. How are adhesion and cohesion similar? How are they different? Cohesion involves the attraction of the same molecules while adhesion involves the attraction of different molecules. 24. Describe surface tension in a group of bonded water molecules. Due to the cohesive nature of a water molecule, surface tension is the tendency for a liquid to resist any outside pressure or force. An example of this is the Argyroneta aquatica (water spider). This spider is able to walk on water due to the weight of the spider being able to balance out the surface tension. 25. Describe the arrangement of water molecules in solid, liquid and gas form. How does the movement of the molecules differ in each form? The solid phase is slower in movement, the liquid phase is has more movement than the solid, but the gas phase is faster than all of the other phases.

26. The density of a substance refers to how close together the molecules in that substance are packed. Compare the density of water in its three phases. When water is a solid we think of an ice cube, this tend to be less dense than liquid water. Liquid water is denser than solid and gas phase water (vapor) is the lightest form of water. Density: Liquid>Solid>Gas 27. Water is often called the 'universal solvent' because it can dissolve more substances than any other liquid. Explain how the polarity of the water molecule makes this possible. Since the hydrogen has a positive charge and the oxygen has a negative charge this makes it possible for water to attract other compounds.

III Biomolecules Navigate to the Molecular Structure of Fat Click and Learn (https://media.hhmi.org/ biointeractive/click/obesity_molecular/01.html). After clicking through the activity, answer the questions below. #28-33 0.5 points each 28. These polymerization reactions are all referred to as dehydration synthesis or condensation reactions. Develop an explanation for why these terms are used to describe these reactions. In dehydration synthesis a water molecule goes in and a monomer comes out while in condensation reaction monomer goes in and water comes out. In all these reactions make fewer products and water is created as a product. 29. These reactions can also be reversed, breaking the large molecule into its individual molecules. What substance would need to be added in order to reverse the reaction? Water would need to be added to reverse the reaction 30. Lysis means to split or separate. What prefix would you add to lysis to mean separate or split using water? “Hydro-” meaning water. 31. Using your answers to the previous two questions, what word is used to describe the reaction that uses water to break apart a large molecule? Hydrolysis 32. Look at the two types of fatty acids below, saturated and unsaturated. What is the difference between the two?

There is a double bond in the unsaturated fatty acid and a single carbon bond chain in the saturated fats. 33. Saturated fats are solid fats, like the animal fats lard and butter, whereas unsaturated fats are more fluid and form oils, such as vegetable oil. Trans fats are plant oils that are artificially solidified to make them suitable for baking purposes. In recent years trans fats have been associated with negative health issues and are not as widely used. Explain in simple molecular terms what would have to be done to a plant oil to transform it to a trans fat.

To transform a plants oil into transfat we would have to add hydrogen molecules. A process called hydrogenation initiates double bonds to occur and make lipids more saturated than they were. Post Lab Questions 1. What are the differences between ionic and covalent bonds? Be sure to refer to valence electrons, metals and non-metals in your response. (1.5 points) An ionic bond is formed between a metal and nonmetal element where the metal loses an electron and donates it to the nonmetal while a covalent is formed between two nonmetals and share electrons equally.

2. How are ionic compounds named? Use specific examples in your answer. (1 point) When naming an ionic compound you have to take into consideration the cation (positive charge) and anion (negative charge) if we have Sodium (Na+) and Chloride (Cl-) it would become NaCl since the positive and negative charge cancel out. Another example is Calcium (Ca2+) and Chloride(Cl-) would become CaCl2 because the calcium donates its two electrons to the chloride.

3. Describe water’s cohesion, and how this helps in cooling or heating our bodies and our planet. (1 point) Cohesion helps similar molecules stick together. When the heat of a solution containing hydrogen bonds is increased, the bonds begin to break and create gas that goes into the air, this helps our planet and body stay at a normal level of heat. 4. Describe how water forms surface tension. (1 point) Surface tension is due to the attraction between water molecules. Since water is “sticky” in nature this helps them better adhere to each other and form bonds with each other that create surface tension 5. Why is a water molecule polar? (1 point) A water molecule is polar because of the shape and the difference in electronegativity (if its higher than 0.5 its polar and if its lower than 0.5 is non-polar) 6. Metabolism is the collective term used to describe all the chemical reactions taking place inside living organisms. Why is water so important for metabolic reactions? (2 points) Every chemical reaction that occurs happens in the presence of water so the organic molecules involved in metabolism will dissolve into the water and make it easier to transport. 7. We store excess food in our body either in the form of carbohydrates (in muscles and the liver) or as fat (adipose tissue). When our body needs additional energy it uses the carbohydrate source first as a source of “quick” energy, then the fat. Why do you think carbohydrates are used as a source of quick energy rather than fat? Use complete sentences and scientific terminology in your response. (2 points) It take less energy to use carbohydrates while fats require a greater amount of energy to break down the bonds. Even though fats contain more energy, the energy in carbs is by far easier to access....