Progressions are important. If I dove straight into a max effort weight training and health kick, I would get disappointed in the results. It would be frustrating and feel impossible. I need to progress through logical stages to get there. At least that’s what my “mid-January” self is telling my “New Year’s Resolution” self. Just one step at a time.
It’s the same for your students when writing formulas for compounds. Some are ready to go in seconds. Others can feel the swirl of all the terminology floating in their head and they struggle to make sense of the foreign-sounding language. They need a progression. Here is the progression that I have taken my kids through this year in writing ionic formulas.
Start before they know it
I made the on-ramp even longer this year. I started talking about ionic compounds two chapters before I “really taught” ionic compounds. I put it in terms of reacting in a 1:1 ratio. I did it during the electron structure chapter. They learned about valence electrons. They learned the octet rule. Then I started asking the question, “Which element would react in a 1:1 ratio with potassium?” They started to see the “lose one, gain one pattern”. I repeated the idea in the periodic trends chapter. All along they were starting to see ratios.
Use the least common multiple method
In the compounds chapter, I teach the least common multiple method. I wrote another blog about it, so I won’t spend a lot of time here. Students start to see the transfer of electrons. They see the balancing of the charges. And it feels familiar due to the onramp I’ve been building.
Play the yellow level of CHeMgO
For years, I made my own bingo games to help kids practice. By all means, make your own game. But in case you want it done for you, with four levels of challenge, check out CHeMgO. The first round is with single-element ions. The students are playing bingo while writing in the formulas to balance the charges. The whole class is competing. The winner of each round gets to ask one question on the test, “Mr. Koch, is this right?”. And I will tell them if they are right. I like that better than extra credit.
This is a fun way to push through the early progression. We play two rounds. At the end of the round, everyone has to “black out” their board by filling in all the missing spots. That’s 25 ionic compounds. Since we play two rounds, that’s 50 practice problems.
Introduce cations with more than one charge
Transition metals often have more than one charge. Since I do electron structure and periodicity before naming, they are well aware of the d-block. This progression is pretty fast.
A fun way to introduce the need for Roman numerals is to find two kids that have the same first name in the class. I spice it up. “Did you hear that Johnny went a date with a senior last night?” The kids look around at the two Johnny’s in the class. Wouldn’t it be nice to know which Johnny it was? The story would only get better if I identified which Johnny I was talking about. Enter Roman numerals. You are just identifying which copper ion we are talking about.
To further strengthen this idea, when I write the parenthesis for the Roman numeral I always clearly say, “With a charge of…” The kids start to clarify in their mind that the parenthesis mean “with a charge of.” It’s an identifier of which ion, not how many.
Play the red level of CHeMgO
Now we make the next progression in the game; compounds that use Roman numerals. Play two rounds of bingo. That’s 50 practice questions. I hand out some more questions that kids can ask on the test. I just write their name in the corner of the board if they win. If they win more than once, they get a tally. When they ask “Mr. Koch, is this right?” on the test, I just erase their name. It’s pretty simple.
Add polyatomic ions
The first thing I hand out in the naming unit is a polyatomic ion sheet. I’m not meaning to open a can of worms here, because teachers have BIG opinions on this, but I make my students memorize 21 polyatomic ions and the charges. A quiz over those ions is the first grade of the new semester. After they take the quiz, they have a smaller reference sheet on the back of the periodic table they can use if needed.
Since kids have been using the least common multiple method for writing formulas, it’s not a huge stretch to add the ions that they already know. Some kids will struggle recognizing the charge on the ion is for the entire ion. It sounds silly to us, but it’s true. I really stress that the entire ion has that charge.
Play the purple level of CHeMgO
The next progression is to play bingo that includes polyatomic ions. Same as the time before. They get 50 practice problems couched in the context of a competitive game.
Add acids
The final progression is to add acids. I like to teach acids right after ionic compounds due to the balancing of charges. I have a flow chart that I use to go from formula to name. Most kids look at it, get it, and then don’t use it. But for some, it can be helpful to track. (Download it on the Resources Page here.) Obviously, the names of acids take a little bit more time to practice than ionic compounds. Once they have started using the flow chart and then categorizing acids on their own, it’s time to play again.
Play the pink level of CHeMgO
The next game includes H+ as one of the required ions for everyone. That way they are practicing all the skills they have gained in the progression but also acids. They complete the game board with 50 more practice problems.
I have found this progression of ionic formula writing to be very beneficial. They are learning new content, then applying it immediately in a fun way. By the time they are through, they have completed 200 practice problems without a standard “worksheet” in sight. They are just playing games that progress harder and harder. And they start to find it easier and easier. That’s a good progression.
If you are interested in an ionic formula bingo game that has all four levels of challenge built in, check out CHeMgO. With printable score sheets for the kids, you can be ready to play in seconds. No set up. Just choose your level of challenge and go!
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