My students have always struggled with nomenclature. Even at the end of the unit, I had students mixing up the roman numerals with the molecular prefixes and they would give answers such as Copper Monoxide (II) or Mononitrogen (III) trihydride (I). I decided to try a new approach this school year. One of the Cross Cutting Concepts in NGSS is to look for Patterns. Instead of telling my students what the “rules” for writing ionic compounds are beforehand, I put a list of examples on the board as a Do Now. I asked my students to look for patterns and write down in their own words what they think the rules are. You can see the prompt I used in figure 1.
Figure 1: Finding Patterns Prompt 1
Students were able to recognize that each of the compounds begins with a metal and ends with a non metal. They were also able to identify that the metal of each compound seems to lose the same amount of valence electrons that the non metal gains to fill their octet. Students recognized that the cations were listed first and the anions were listed second. We spent some time practicing how to write neutral compounds and balance charges. We call this method the “Drop and Swap,” while I have heard some people call it the “Criss-Cross method.” Once students mastered this skill, I put the next prompt on the board to have students look for the pattern to name ionic compounds (see figure 2).
Figure 2: Finding Patterns Prompt 2
You can download the Ionic Formula and Naming Patterns Prompts in the Supporting Information. (Readers must log into their account to access. Not a member? Register for free!)
My students were able to create a list of rules to follow when naming ionic compounds. Collectively, they stated that one should name the metallic ion first, and the non metallic ion second. They were all able to recognize that the non metallic ions ended in -ide. The students spent some time doing practice problems and then using their laptops, began to play the MatchMaker Bonding Game created by Steve Sogo from the AACT website. The MatchMaker Bonding Game is scaffolded with multiple versions. Students can start the game practicing ionic bonding with monoatomic ions, move up a level to try polyatomic ions and even challenge themselves with a mix of monoatomic and polyatomic ions. There is also a competition round and a list of salts they can choose from. There is a companion worksheet available as well. As of today, this seems to be available without membership.
Once the students have had more practice and feel more comfortable, the next activity the students worked on was a hands on Ionic Bonding Puzzle Activity that Martin Palermo shared with me: Naming and Formula Writing Investigation (see the Supporting Information for a copy). (This version is available on AACT (requires a membership), a digital version can be found here, and many others are available via Google search). I like to use card sorts where students can hold the pieces in their hands, move them around and fit the pieces of the puzzle together.
Figure 3: Ionic Bonding Puzzle Activity
I also had my students do a Speed dating activity that I found on Sciencespot.net. Each student is handed a card with either a cation or anion listed on it. The students are instructed to try to make as many matches as possible with all of the students in the room to whom their ionic charge would be attracted to. After the allotted time has passed, students go back to their seats, write the neutral compound’s chemical formula and name all of the compounds that were created. You can also scaffold this activity by including polyatomic ions and eventually include transition metallic ions with multiple oxidation states that use roman numerals (stock system).
Upon completion of all of these activities, my students have proven to have a strong understanding of the rules for naming and writing ionic compounds. By allowing students to determine the pattern and create their own list of rules, the students took ownership of their learning and deepened their comprehension of the content as seen by their assessment scores.
