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Review: Names and Formulas
of Molecular Compounds
plus Lewis Diagrams

Follow the instructions given for each section of this worksheet. You will need your periodic table, a quiet place to work, and your wits to complete this homework. Also, you may find it helpful to refer back to the text of the activity you did prior to this homework.

Text Review

Answer the following questions using complete sentences.
  1. What is the difference between a compound and an element?
  2. What are the characteristics of metallic elements? Where are they found in the periodic table?
  3. Describe the properties of non-metals. Where are they found in the periodic table?
  4. What kinds of elements are involved in most molecular compounds?
  5. What is a diatomic molecule?
  6. Is it necessary for a diatomic molecule to be made of two of the same atom? Explain.
  7. Which elements exist in pure form as diatomic molecules? (Remember, you must memorize these!)
  8. What are some compounds that are diatomic molecules?
  1. Describe the behavior of electrons in a covalent bond between atoms. How do the electrons keep the atoms bound together?
  2. What are the physical characteristics or properties which differentiate ionic compounds from molecular compounds?
  3. Compare and contrast the types of elements found in the chemical formulas of molecular compounds and ionic compounds.
  4. How many valence electrons do elements in groups 1, 2, and 13 - 17 have? In other words, what is the elemental Lewis diagram (how many dots) for an element in each group?
  5. Draw the usual bonding pattern for elements in groups 1, 2, and 13 - 17.
  6. How many bonds is typical for each group?
  1. In your own words, write down the correct procedure for writing a name for a molecular compound from its formula. Enrich your procedure with examples such as how to name these compounds: NO, BrI, BrI5, P4O10.


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Lewis Diagrams, Names, and 3-D Shapes

For the molecules on this page write the name or formula, whichever is missing, and then draw the Lewis diagram showing the structure of the molecule. For each molecule write down the total number of valence electrons. For each molecule, write down the 3-D shape. The shapes will all fall into these categories: linear, trigonal planar, bent, tetrahedral, or trigonal pyramidal. Use your own paper to do this work.

Hints: If the central atom is a metal it is likely to have fewer electrons in the correct molecule than an octet. If the central atom is C, N, O, or F then it must have an octet. If the central atom is P, As, S, Se, Te, Cl, Br, or I then sometimes it may have greater than an octet in the final, correct molecule.

  1. CO
  2. BF3
  3. CH4 (methane)
  4. NH3
  5. O3 (ozone)
  6. H2O
  7. CO2
  8. H2S
  9. NO2– (nitrite)
  10. O2
  11. HCl
  12. AlBr3
  13. CCl2F2 (dichloro-difluoromethane)
  14. NF3
  15. ClO3– (chlorate)
  1. HCN (hydrogen cyanide)
  2. CH3OH (methanol: one H is connected to O)
  3. H3O+ (hydronium)
  4. OF2
  5. BeCl2
  6. CH2O (formaldehyde)
  7. SiH4
  8. SO32– (sulfite)
  9. ClO2– (chlorite)
  10. H2O2 (hydrogen peroxide)
  11. CO32– (carbonate)
  12. NH4+ (ammonium)
  13. PO43– (phosphate)
  14. AsI3
  15. Cl2
  1. carbon tetrachloride
  2. phosphorous trihydride
  3. sulfur trioxide
  4. sulfur dioxide
  5. hydrogen monofluoride
  6. germanium tetrabromide
  7. nitrogen triiodide
  1. oxygen dichloride
  2. phosphorous trichloride
  3. dioxygen difluoride
  4. magnesium difluoride
  5. aluminum trichloride
  6. nitrogen
  7. iodine


Lewis Diagrams for Ionic Compounds

Draw the Lewis diagram of the ion formed from each element in the pairs below. Also, create ionic compounds from each pair of elements and write the correct chemical formula.

  1. Na and Cl
    Lewis Diagrams of Ions:
    Chemical Formula for the Combination:
  2. Mg and F
    Lewis Diagrams of Ions:
    Chemical Formula for the Combination:
  3. Al and Br
    Lewis Diagrams of Ions:
    Chemical Formula for the Combination:
  4. K and S
    Lewis Diagrams of Ions:
    Chemical Formula for the Combination:
  1. Ga and I
    Lewis Diagrams of Ions:
    Chemical Formula for the Combination:
  2. Li and N
    Lewis Diagrams of Ions:
    Chemical Formula for the Combination:
  3. Ba and P
    Lewis Diagrams of Ions:
    Chemical Formula for the Combination:
  4. Ca and O
    Lewis Diagrams of Ions:
    Chemical Formula for the Combination:
Solutions to the Molecular Names and Lewis Structures exercises
This homework belongs with the Chemical Nomenclature of Molecular Compounds group activity.
Additional Practice and Review
ChemTeam Additional Naming Information and Practice
(has lots of exercises with answers) Last updated: Jan 20, 2021       Home