Atoms & Elements Homework Problem Set

1. How many protons, neutrons and electrons are present in one atom of the following:
   1. ¹H
   2. ²H
   3. ³H
   4. ¹³N
   5. ¹⁴N
   6. ¹⁵N
   7. ⁷⁹Br
   8. ⁸¹Br^1-
   9. ²⁶²Bh

2. What is the Atomic Weight of chlorine given that:
   • The exact mass of ³⁵Cl is 34.9689 and the relative abundance is 75.53%
   • The exact mass of ³⁷Cl is 36.9659 and the relative abundance is 24.47%
   Is this the answer that you expected?

3. What is the Atomic Weight of ruthenium given the following information from WebElements:

   Isotope	Abundance	Exact Mass
   96Ru	5.54%	95.907599
   98Ru	1.87%	97.905287
   99Ru	12.76%	98.9059389
   100Ru	12.60%	99.9042192
   101Ru	17.06%	100.9055819
   102Ru	31.55%	101.9043485
   104Ru	18.62%	103.905424

   Is this the answer that you expected?

4. Using a blank periodic table, fill in the atomic number, name, atomic symbol, and atomic weight of the first 36 elements. Also label the noble gases, the halogens, the alkali metals, the metals, and the non-metals.

5. Use the mass spectrum for chromium given below to determine the atomic weight.

6. For the following molecules; write the chemical formula, determine how many atoms are present in one molecule, determine the molecular weight, determine the number of moles in exactly 1 gram, and the number of moles in exactly 10^-6 gram.
   1. carbon dioxide
   2. iron (II) chloride
   3. zinc (I) oxide
   4. dinitrogen pentoxide
   5. potassium fluoride
   6. dihydrogen monoxide
   7. iron (III) sulfate
   8. lithium acetate

7. Name the following compounds, determine the molecular weight, determine the percent composition, and determine how many moles in 8.35 grams of the compound.
   1. KI
   2. CaF₂
   3. Cu₂SO₄
   4. Cr(NO₃)₆
   5. NO
   6. NO₂
   7. N₂O
   8. N₂O₄
   9. LiOH
   10. SO₂

8. Give the chemical formula (or atomic symbol), molecular (or atomic) weight, and charge for the following ions:
   1. sulfate
   2. sulfite
   3. nitrate
   4. hydroxide
   5. nitrite
   6. chloride
   7. nitride
   8. bromide
   9. acetate
   10. carbonate

9. Calculate the number of moles in:
   1. 20.1797 g of Ne
   2. 45.3594 g of Ne
   3. 0.198669 g of Ne
   4. 0.198669 g of Ta

10. Calculate the mass of:
    1. 1.00 mol of Fe
    2. 2.00 mole of Fe
    3. 4.362 x 10^-5 mol of Fe
    4. 4.362 x 10^-5 mol of Li

Scott Van Bramer
Department of Chemistry
Widener University
Chester, PA 19013

© copyright 1996, S.E. Van Bramer
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Last Updated: Monday, June 04, 2001 2:19:17 PM