How are isotopes of an element different from one another? How are they the same? (10 points) Isotopes make up an element, and therefore will have the same number of protons. Isotopes are different from one another because they will have different neutrons. 2. Are mass number and atomic mass the same thing? Why or why not? (10 point s) Mass and atomic number are not the same. The mass of an element is the number of protons and neutrons in the nucleus combined. An element’s atomic number tells us how many protons there are, and the difference between the mass and atomic number is the amount of neutrons that are in he nucleus.
Atomic mass is the weighted average mass of all isotopes based on abundance. This means that we will take the mass of each isotope and multiply it by its percent abundance. We would then add those values together to find the average atomic mass. 3. Use the concepts of relative abundance and relative weight to explain why carbon has an atomic mass of 12. 011 amu when there are three isotopes of carbon weighing 12 amu, 13 amu and 14 amu. Wouldn’t the average of these three be 13, instead of 12. 011? (10 pts. When calculating average atomic mass of Carbon, we would multiply the ass of each isotope by their respective relative abundance. We would then combine the resulting numbers to find the average atomic mass of 12. 011 amu. Since each isotope’s atomic mass is not a whole number, it would not be possible for the average atomic mass to be 13. According to page 124 of our textbook, the most prevalent Carbon isotope is 12, meaning it occurs the most often. This helps to support why the atomic mass is closer to 12 than 13. 4. Which isotope of beanium had the greatest effect on the calculated atomic mass for beanium?
How do you know this? Was this what you expected? Why or why not? (1 0 points) believe that Pintobeanium had the greatest effect on the calculated atomic mass for beanium because Pintobeanium had both the most relative abundance and relative weight and therefore made up just over 50% of the total relative weight. This does somewhat surprise me, as initially I would have expected that Kidneybeanium would have the greatest effect because the average mass is greater than that of pintobearmum. 5. Explain what relative weight is and why it is important to the calculation of atomic mass. 10 points) Relative weight is calculated by the mass of an isotope by and multiplying it by the relative abundance of the isotope. This is important as the relative weights of the isotopes in an element are combined to find the atomic mass, or weighted average, of that particular element. Part II 6. Using the list complied in Part II of the lab, identify the similarities between substances with similar functions. Give three examples. (20 points) part II was interesting because it helps to identify the chemicals that we use every day. Two examples of chemicals used in photograph are NH4Br and
NH4Cl – both of which contain ammonium. Chemicals used in fertilizers are also very similar, in that both of the chemicals contain ammonium (NH4N03 and [NH4]3P04). Lastly, NaCIO and Ca(CIO)2 have similar functions in that both are used to disinfect; NaClO is bleach and Ca(CIO)2 disinfects swimming pools. It’s very interesting to see how two different yet similar compounds can do a very similar function, if not the same, as one another. Part Ill 7. What elements did you identify for Unknown #1, Unknown #2, and unknown #3? (12 points) Unknown 1: Chlorine unknown 2: Cesium Unknown 3: Strontium .
For Unknown #1, explain your reasoning in determining this identification. (10 points) looked at all five factors of unknown 1 and decided to begin with “gas at room temperature. ” From lesson 4, we learned that one property Of metal is that, aside from mercury, all metals are solids at room temperature, which means that groups IA and 2A are not possible groups for this element to be in. Next, noted the yellow-green gas and how the element is slightly soluble in water. The only other element in the note cards that is a yellow gas and is slightly soluble in water is Fluorine.
This lead me to believe that the element is Chlorine, which I verified by utilizing the interactive periodic table that was available in lesson 4. 9. For unknown #2, explain your reasoning in determining this identification. For unknown 2, I tried to identify elements that were both soft, silvery white and reacted vigorously with water. Barium and Rubidium both have these two traits, but Rubidium is in group IA and Barium is in group 2A. In looking at the melting points for both of these elements, I noticed that Rubidium has a melting point of 312 K, which is much closer to 302 K than Barium is (1 000 K).
