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Homework: Chemical Formulas II

When answering questions use complete sentences. The point of the questions is to show me that you learned something.

When you write only a few words you are telling me that either (a) you learned practically nothing, (b) you did not understand the lesson, (c) you are too lazy to be bothered, or (d) you think I am wasting your time. Whatever the reason, only complete sentences will receive full credit!

Part I

  1. Why must the ions in an ionic compound be mixed in particular proportions?
  2. When you write the formula of an ionic compound what role do the charges on each ion play?
  3. What is it about electrolytes that makes them capable of carrying an electrical current when they are dissolved in water?
  4. Explain how the name of an ionic compound can be enough to tell you how many of each ion is present in the formula of that compound. Use the following examples, Iron(II) Chloride, Iron(III) Chloride, Ammonium Carbonate, and Aluminum Oxide.
  5. Explain why you can’t change the subscripts in the formulas of polyatomic ions like PO43- or NH4+.
  6. Which part of the periodic table has elements that are more electronegative than other elements? (Use group numbers). Which element is the most electronegative element?
  7. Which part of the periodic table has elements that are less electronegative than other elements? (Use group numbers). Which element is the least electronegative element?
  8. What does it mean when a chemist says that a bond between two atoms is polar?
  9. What does it mean when a chemist says that a bond between two atoms is non-polar?
  10. What does it mean when a chemist says that a bond between two atoms is ionic?
  11. Use the concept of electronegativity to explain the solubility rule that “Like dissolves like”.


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Part II

Write the ionic form of each of the following elements, showing the charge you would expect it to have based on its location in the periodic table. Then build a compound from those ions, writing a chemical formula. Also, write the name of the compound. Remember, the total positive and negative charges must be equal so that the compound is neutrally charged.

  1. Rubidium, Iodine
  2. Calcium, Nitrogen
  3. Strontium, Bromine
  1. Magnesium, Oxygen
  2. Gold(IV), Chlorine
  3. Potassium, Phosphorous

Part III

Name the following compounds.

  1. CrO3
  2. PCl3
  3. NO
  4. Cr2O3
  5. Ag2S
  6. N2O4
  7. MnO2
  8. N2F4
  9. CsF

  1. KClO3
  2. BaSO3
  3. HgSO4
  4. NH4Cl
  5. Pb(OH)2
  6. Ca(NO3)2
  7. Sn(CO3)2
  8. CuNO3
  9. Ti3(PO4)4

Part IV

Without looking at the chart of electronegativity values circle the element that is more electronegative in each of the following pairs. Use your understanding of the overall trend to help you.

  1. O Na
  2. P K
  3. Rb Al
  1. C F
  2. F I
  3. O Se

Part V

Write formulas for the following compounds.

  1. Sulfuric Acid
  2. Carbon Dioxide
  3. Ammonium Sulfate
  4. Barium Nitrate
  5. Calcium Phosphate
  6. Tin(IV) Iodide
  1. Hydrochloric Acid
  2. Methane
  3. Zinc Bromide
  4. Ammonia
  5. Chromium(II) nitrate
  6. Potassium Cyanide
This homework belongs with the Chemical Formulas and Compounds group activity.
Many problems were inspired by those at Mr. Basset’s Site.
Last updated: Apr 18, 2007        Home