WA02_CHE-121-mar14 - Thomas Edison State College General...

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Thomas Edison State College General Chemistry I with Labs (CHE-121) Section no.: OL009 Semester and year: May 2015 Written Assignment 2: Atomic Structure and Chemical Compounds Answer all assigned questions and problems, and show all work. 1. What is the mass number of an iron atom that has 28 neutrons? (3 points) Mass number = 26 + 28 = 54 (Reference: Chang 2.13) 2. Calculate the number of neutrons of 239 Pu. (3 points) (Reference: Chang 2.14) 239 (mass) – 94 (protons) = 145 (neutrons) 3. Write the appropriate symbol for each of the following isotopes: (a) Z = 11, A = 23; (b) Z = 28, A = 64 (6 points) a. 11 23 Na (Reference: Chang 2.17) b. 28 64 Ni 4. Define, with two examples, the following terms: (a) alkali metals, (b) alkaline earth metal, (c) halogens, and (d) noble gases . (8 points) a. alkali metals: Li, Na b. alkaline earth metals: Mg, Ca c. halogens: F, Cl d. noble gases: He, Ar (Reference: Chang 2.22) 5. Identify the following as elements or compounds: (a) NH 3 , (b) N 2 , (c) CO, (d) Co, and (e) He. (5 points) 1 Copyright © 2014 by Thomas Edison State College. All rights reserved.
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a. NH3 = ammonium d. Co = cobalt b. N 2 = dinitride e. He = helium
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  • Spring '15
  • Khurana
  • Chemistry, Atom, Chemical element, Alkaline earth metal, Thomas Edison State College

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