Lab 3 Write Up PDF

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Laboratory 3: Write Up Assignment 1. Choose Sodium (Na). What type of element is it and how many valence electrons does it have? Na is a metal; it has 1 valence electron 2. Choose Fluorine (F). What type of element is it and how many valence electrons does it have? F is a non-metal; it has 7 valence electrons 3. Answer the question on the screen, “What type of bond is this combination likely to form?” The combination of Na and F 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. 1 atom of Na and 1 atom of F were used. Na lost avalence electron, becoming positively charged, while F gained a valence electron, becoming more negatively charged. 5. What does the positive (+) charge indicate (mention specific subatomic particles in your answer)? the (+) charge indicates that the atom lost an electron, becoming a cation. 6. What does the negative (-) charge indicate (mention specific subatomic particles in your answer)? the (-) charge indicates that the atom gained an electron, becoming an anion. 7. What is the final overall charge The final overall charge is neutral 8. What is the name AND formula for the compound formed? Sodium fluoride, or NaF. 9. Choose Calcium (Ca). What type of element is it and how many valence electrons does it have? Ca is a metal with 2 valence electrons. 10. Choose Chlorine (Cl). What type of element is it and how many valence electrons does it have? Cl is a nonmetal with 7 valence electrons. 11. Answer the question on the screen, “What type of bond is this combination likely to form?” This combination is likely to form an ionic bond. 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. 1 Ca atom, and 2 Cl atoms. the 2 Cl atoms each gain an electron from Ca. 13.What is the final overall charge? What is the name AND formula for the compound formed? The final overall charge is neutral, and the name is Calcium Chloride; CaCl2 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

# Valence electrons

Charge

Atom #2

# Valence electrons

Charge

Formula

Formula Name

Na

1

1+

O

6

2-

Na2O

Sodium oxide

K

1

1+

F

7

1-

KF

Mg

2

2+

Cl

7

1-

MgCl2

Potassium fluoride Magnesium chloride

Ca

2

2+

N

5

3-

Ca3N2

Calcium nitride

Al

3

3-

S

6

2-

Al2S3

Aluminum sulfide

Part B: Covalent Bonding 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 in each fluorine atom. 16. Is a fluorine atom a metal or a non-metal? A fluorine atom is a non-metal 17. Did the combination of these atoms create a covalent or ionic bond? The combination created a covalent bond. 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 valence electrons organized to share 2 equally in order to each be surrounded by 8 electrons. 19. Select 2 oxygen atoms. How many valence electrons are in each oxygen atom? Each oxygen atom has 6 valence electrons. 20. Is an oxygen atom a metal or a non-metal? An oxygen atom is a non-metal. 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? The combination of these atoms created a covalent bond. 4 valence electrons were shared equally between the 2 atoms. 22. How is this bond different from the bond in the fluorine molecule in question 1? This bond is different because the 2 oxygen atoms form a double bond. II. Properties of Water Virtual Lab 23. How are adhesion and cohesion similar? How are they different?

Adhesion and cohesion are similar in that they both have to do with sticking to things. Adhesion has to do with water sticking to other things, while cohesion has to do with water molecules sticking to themselves. 24. Describe surface tension in a group of bonded water molecules. The hydrogen bonding of the water molecules creates a film on the surface, which is why very light bugs and things can walk across bodies of water. 25. Describe the arrangement of water molecules in solid, liquid and gas form. How does the movement of the molecules differ in each form? Hydrogen bonds between water molecules are closer together in liquid form than in solid form. This is why liquid water is less dense than ice. The bonds are further apart, or broken when heated and turned into gas. 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. The molecules are packed closest together in liquid form than as a solid. They are broken when heated and turned into a 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. The charges on the hydrogen and oxygen atoms attract other molecules and surround them in a solution. III Biomolecules 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. These terms are used to describe these reactions because one “uses up” water (just like something dehydrating), while the other “produces” water (just like condensation on a window). 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? Energy in the form of ATP 30. Lysis means to split or separate. What prefix would you add to lysis to mean separate or split using water? Hydro31. 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?

The fatty acid on the right has a double carbon bond, while the one on the left has all single bonds. 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. Double bonds in the plant oil would have to be broken in order to give the fatty acid chains a straighter configuration which would allow them to be packed closer together. 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) During an ionic bond, valence electrons are transferred from a metal to a non-metal. During a covalent bond, valence electrons are shared between a metal and a non-metal.

2. How are ionic compounds named? Use specific examples in your answer. (1 point)

Ionic compounds are named by beginning with the full name of the metal and following it with the name of the non-metal but adding the suffix -ide, as in Sodium chloride, or Magnesium sulfide.

3. Describe water’s cohesion, and how this helps in cooling or heating our bodies and our planet. (1 point) The hydrogen bonds in water create a surface tension known as cohesion. Due to the hydrogen bonds, water has the ability to absorb large amounts of energy before they are broken. When the bonds are broken, they release the energy in the form of heat. This is why we cool down when we sweat, and why oceans help keep the planet from overheating. 4. Describe how water forms surface tension. (1 point) Surface tension in water is formed by the hydrogen bonds between the hydrogen and oxygen molecules. This creates a web-like connection which allows very light objects to rest on top, even if they are more dense.

5. Why is a water molecule polar? (1 point) Water is a polar molecule because the electrons are shared more by the oxygen molecule than the hydrogen molecules. 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) Water is so important for metabolic reactions because of its ability to break apart larger chemicals into smaller ones for various uses. It is also good at breaking apart ionic compounds such as Sodium chloride into individual sodium and chlorine atoms. 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) Carbohydrates are used first because the body can use an anaerobic process to get energy which conserves the body’s overall energy storage in case it is needed later....