Summary

In this lesson, students will demonstrate their knowledge of ionic bond strength using a “brackets” activity. Pairs of students start the activity playing a game of “Ionic Compound War” to build eight compounds. Then then transfer the compounds to a “bracket” and use their knowledge of ionic bonding, along with a solubility chart, to predict the strongest and weakest bond between four pairs of ionic substances.

Grade Level

High School

NGSS Alignment

This lesson will help prepare your students to meet the performance expectations in the following standards:

• HS-PS1-1: Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
• HS-PS1-2: Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.
• Scientific and Engineering Practices:
  • Analyzing and Interpreting Data
  • Engaging in Argument from Evidence

Objectives

By the end of this lesson, students should be able to

• Name and write the formula for ionic compounds.
• Estimate the relative strength of an ionic bond in two substances.
• Use a solubility table or chart to determine the solubility of ionic compounds

Chemistry Topics

This lesson supports students’ understanding of

• Ionic Bonding
• Chemical Formulas
• Solubility
• Ionic Bond Strength

Time

Teacher Preparation: minimal

Lesson: 45 - 60 minutes

Materials

• Student Handout and War Cards

Teacher Notes

• Ionic bond strength varies, depending on the ions that are present in the compound. As a general rule:
  • Ionic bonds resulting from ions with higher charges will generally have higher melting points and lower solubility than those with lower charges.
  • Ionic bonds between ions with smaller radii with generally have higher melting points and lower solubility than those with larger radii.
• It is important to stress that these rules are general rules, not absolute trends.
• This activity should be used as a summative assessment following a comprehensive study of ionic compounds and bonding.
• There is a chance that the compounds that the students compare might have both different charges and radii. In that case, students should use the solubility information and make the best prediction they can based on the data for the two compounds.
• Students should be in pairs. Make one copy of ion cards for each pair.
• Have students cut up cards, keeping the anions and cations separate.
• One student should have a set of anion cards and the other set of cation cards.
• Students should hold their card set face down and shuffle them well.
• The pair then flips their cards one at a time, and write the correct formula and name for their cation/anion combination in the table.
• They should then predict the solubility of each compound.
  • Depending on your class level, you can provide them with the solubility rules and/or table.
  • If you require your students to memorize these rules, disregard the table.
• Once finished, each team will transfer their compounds to the bracket.
• Once the first round of the bracket has been filled in, the pair predicts the strongest ionic bond/lattice energy for each pair and completes the bracket.
• The central question in this activity is, “Which compound has the strongest ionic bond?” This question can easily be changed, depending on the level of your class:
  • Predict which compound will be most soluble.
  • Predict which compound will be most soluble.
  • Predict which compound will have the lowest melting point.
  • Predict which compound will have the highest melting point.