Chemistry can feel dangerous to a student. There are so many pitfalls that you and I so easily avoid, and yet the students repeatedly fall in to. As you get more experienced (I was going to say older, but that hurt my feelings) as a teacher, one of the biggest gifts you can give your students is the ability to avoid those traps. This article will point out a few of the traps in naming compounds and how I help students avoid them.
The alphabet soup trap
You and I can look at a compound and instantly know what type it is. But students, who are really starting to look at compounds for the first time only see randomness. I had a student in for office hours last night who was aware enough to tell me that he just sees letters. That’s it. No charges. No metals and nonmetals. Just letters. To beat the alphabet soup trap, the students need to start picking up patterns.
I use this flow chart (free download here). It is simply a way to help them start thinking in order. Does the formula start with H? Then it’s an acid. Does it have two nonmetals? Then it’s a molecular compound. Is it a metal and a nonmetal? Ionic. They have to know where to start or they will use horrific mixes of the naming conventions.
The ate, ite, ide trap
Students will end compound names with whatever they feel like. That’s a trap. You and I know that there is a difference between sodium chloride, sodium chlorite, and sodium chlorate. But early on, the students think it’s all just semantics. They make it sound nice.
This is one reason that my students have to memorize a selection of polyatomic ions. They recognize them as a unit they have seen. This is another challenge. Some students don’t see ions as unit. They see ammonium as an N and then some H’s. That changes how they try to name things as well as messing up their ability to balance charges.
I say it so many times in class. The “ides” are on the front of the periodic table. The “ates” and “ites” are on the back. Our periodic table has a table of selected ions on the back. (You can get them free from Montana Tech University if you just ask. They will also give you a free wall poster sized one.) If the name is sodium chloride, that anion is on the front, meaning it is just Cl. If it is sodium chlorate, the “ates” are on the back. This helps trigger in their mind that they are working with a whole unit as an anion.
Roman numeral trap
Some ionic compounds need Roman numerals and others don’t. This can seem arbitrary to the struggling student. I use a silly little story to help. I teach at a small school of around 400 kids. There is a student named Taige that everyone knows. It’s a unique name and there is only one Taige in the school. When the students look at magnesium in a compound, I ask them if there is more than one charge or type of magnesium. There isn’t. So it’s like saying “Taige is on the Science Bowl team.” I don’t have to use any further idenitifiers. Everyone knows which Taige I’m talking about. But if I said “Noah is on the Science Bowl Team” they wouldn’t know who I ‘m talking about. Evidently, Noah was a real popular name about 16 years ago, because we have a ton of them. In order to know which Noah I’m talking about I have to include an identifier. In the case of the compound, the identifier is the charge. It’s like a last name. Use identifiers for cations only when you need to.
The parenthesis trap
When writing formulas, many students will not use parenthesis when they should. It helps if the students recognize polyatomic ions as a unit. But they still get hung up. For example, if the compound was aluminum carbonate, many times they feel like they have already balanced the charges due to the subscript of 3 in carbonate. If they recognize carbonate as a unit, they will see that the least common multiple is six and therefore they need three total units of carbonate. Keep reinforcing the unit nature of polyatomic ions. I wish I had a better way to help them avoid this trap. If you have a good way, then please share it in the comments!
The overwhelm trap
This isn’t just for names and formulas. This is for humans. Chemistry can feel like a really big challenge for kids. And the white flag is easy to pull out. Just surrender. But we have to keep encouraging the kids to fight. Just yesterday, the day before the test, one of my students was aggressively waiving her proverbial white flag. But as I worked with her, it became clear that it wasn’t just chemistry she was battling. It was life. It is moments like that when teachers can give a little life. I showed her how she was winning some chemistry battles. She could do things. Every correct move resulted in praise. She heard the praise but was still struggling. After class, I asked her one favor.
“Sally*, I need one favor from you.”
“What’s that?”
“Believe in Sally as much as I believe in Sally.”
She looked at me sheepishly and gave a half-hearted nod. She will try. I’m hoping that encouragement allowed her to take one tiny step away from the overwhelm trap. Any trap avoided is a win.
* Of course, her name isn’t Sally. But it could have been any one of your kids.
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