Summary

In this activity, students will be introduced to ionic compound formulas and names. They will group prepared cut-outs to note similarities and differences among different classes of ionic compounds (i.e. binary and ternary, including metals with varying charges). The goal is not to be equipped to write names and formulas for ionic compounds, but to recognize trends in naming.

Grade Level

High School

Objectives

By the end of this activity, students should be able to:

• Pair ionic compound names and formulas.
• Summarize “rules” for naming ionic compounds.
• From the compound name, recognize if it contains a polyatomic ion and/or a metal with a varying charge.

Chemistry Topics

This activity supports students’ understanding of:

• Ionic Compounds
• Naming Compounds
• Metals and Nonmetals
• Polyatomic Ions
• Naming Compounds
• Formula Writing

Time

Teacher Preparation: 10 minutes

Lesson: 20 minutes

Materials (per group)

• 1 set of Ionic Compound Name cards
• 1 set of Ionic Compound Formula cards
• 1 set of Extension naming/formula cards (optional; for groups that desire enrichment)
• Periodic table

Safety

• No specific safety precautions need to be observed for this activity.

Teacher Notes

• Advance preparation: photocopy and cut out each sheet of cards so that each student group gets a set. Laminate, if desired. It is also helpful to color-code each different sheet of cards so that they can be collected from groups accordingly.
• A group size of 3-4 students works well. Each group will need 1 set of each of the cards.
• The extension naming/formula cards are optional, use for groups that desire enrichment.
• Teachers should be familiar with naming and formula writing for ionic compounds. Students should be familiar with periodic table classifications including: metals, nonmetals, transition metals, main-group elements, s, p, d, f blocks, and chemical formulas.
• Teachers should consider which polyatomic ions they want their students to know and adjust the cards accordingly. The Extension Cards should be used if students will be required to know how to get from the –ate to –ite form of a polyatomic ion and/or will not have a reference sheet with all charges of monatomic ions.
• This is an informal activity meant to generate group and whole-class discussion, so it is not essential for students to record anything or to give them a handout. The rational is to allow student to think about categories and connections without an awareness of the guiding questions that lie ahead. For a more formalized activity, the student handout could be distributed.
• Lesson Timing: After each set of cards is distributed, students need about 3 minutes to group them and discuss. Sharing out to the whole class generally takes another 3 minutes. A total of 20 minutes for the activity allows for interactions within groups, whole-class interactions, and a bit of direct instruction by the teacher.
• Carrying out the activity: Instructions and guiding questions for this part are included below. Use the guiding questions with groups as needed. Bullet points contain teacher’s oral instructions to students; [bracketed items] contain teacher actions. Starred (*) questions work best in a whole-group setting.
  • A. Distribute Ionic Compound Name Cards to each group.
    • Organize the 6 cards into 2 categories of 3 cards each. Discuss an appropriate heading for each category. “Miscellaneous” or “other” categories are off-limits. [Teacher should walk around an observe card groupings.]
    • Now re-organize the 6 cards, still with 3 cards in each pile into 2 different categories. [Teacher should walk around and observe card groupings.]
    • *Share your categories with the class. [Teacher can keep track on board.] Which ones do you think make the most sense from a chemistry perspective? How can we best summarize each category heading in sentence form?
  • B. Distribute Ionic Compound Formula Cards to each group.
    • Match the 6 formulas to the names. Raise your hands when the group agrees on the pairings. [Teacher should walk around and observe card pairings. Teacher should tell how many matches are incorrect, but not identify which matches are incorrect.]
    • Now that all groups have correct matches, discuss (or jot down) some summary statements about how you think ionic compounds are named. [If necessary, give the hint: locate each of the metals on the periodic table.]
    • *Please share your summary statements. [Correct any that are inaccurate and note ones that come up several times, so that the class can reach agreement on a few.]
  • C. Distribute Extension Naming and Formula Writing Cards to each group.
    • Match the 6 formulas to the names. [Teacher should walk around and observe card groupings. The teacher should tell how many matches are incorrect, but not identify which matches are incorrect.]
    • Now that all groups have correct matches, what contradictions can you find about each of these matches with regard to your summary statements?
    • *Please share any contractions to summary statements in Part B.
    • *Though the summary statements crafted earlier will be useful in naming the majority of ionic compounds, exceptions such as these exist and will be learned.
  • D. Suggested homework assignment and real-world connection: Bring in or photograph labels from safe, school appropriate household products that have ionic compounds as ingredients. Find an ingredient that ends in –ide, one that ends in -ate, and one that ends in –ite. They can each be on the same label or from three different labels. [Teacher can compile these and use them at the end of the nomenclature unit as formula-writing practice.]
• Expected Answers:
  • A. Ionic Compound Name Cards
    • Common groupings.

    • End with -ide	End with -ate	Contain Roman numerals	Does not contain Roman numerals
      iron (III) chloride potassium phosphide aluminum oxide	copper (II) nitrate calcium sulfate iron (II) chlorate	iron (III) chloride copper (II) nitrate iron (II) chlorate	potassium phosphide aluminum oxide calcium sulfate

    • Suggested summaries:
      • Ionic compounds either end in –ide or –ate. (The reason for each ending isn’t yet known.)
      • Ionic compounds that include transition metals have Roman numerals shown in parenthesis. (The meaning of the Roman numerals isn’t yet known, but the teacher may divulge that the Roman numeral indicates the positive charge of the metal.)
  • B. Ionic Compound Formula Cards
    • Properly matched names and formulas.

      • Name	Formula
        iron (III) chloride	FeCl3
        potassium phosphide	K3P
        aluminum oxide	Al2O3
        copper (II) nitrate	Cu(NO3)2
        calcium sulfate	CaSO4
        iron (II) chlorate	Fe(ClO3)2

  • The two that are generally mismatched are iron (II) chlorate and iron (III) chloride.
  • Suggested summaries:
    • Ionic compounds containing only two elements end in –ide. [Teacher may choose to introduce the term “binary.”]
    • Ionic compounds containing three elements, one being oxygen, end in –ate. [Teacher may choose to introduce the terms “ternary” and “polyatomic ion.”]
  • C. Extension Naming and Formula Writing Cards
    • Properly matched names and formulas.

    • Name	Formula
      silver bromide	AgBr
      tin (II) chlorite	Sn(ClO2)2
      barium hydroxide	Ba(OH)2

    • Contradictions to summary statements:
      • Silver is a transition metal, but doesn’t have a Roman numeral. [Teacher may opt to say that, for most transition metals, the charge varies, but for silver it’s always +1.]
      • There is a third ending, -ite. [Prompt students to look at the difference between the formula for chlorate and chlorite and come to the conclusion that chlorite ion has one fewer oxygen than chlorate ion.]
      • Ba(OH)₂ has three elements in it, but ends in –ide.
      • Reiterate that, though the summary statements crafted earlier will be useful in naming the majority of ionic compounds, exceptions such as these exist and will be learned.
• Differentiation: Lower-level students tend to need more guiding questions; higher level students may desire more examples in Part C. More examples could include: a compound with the perchlorate ion, a nonionic compound named using prefixes, a zinc compound.