Wednesday, October 15, 2014

Nomenclature: it's all in the cards!

Using the cards and cut outs to write chemical formulas
Nomenclature is a difficult topic to teach new chemistry students because of all the rules.  Is it ionic, molecular, multivalent, polyatomic, or a common name?  Sometimes the hardest part of this whole process is teaching kids to recognize the clues that tell them which rules apply to a a compound.  Nineteen years later, I have finally found a way to teach nomenclature that really works and is fun!  I have a series of card sets that I use to teach kids how to name ionic and binary molecular compounds that makes this lesson so much easier for everyone.

I love my demo sized ion cut outs.
I start the lesson with the basic definition of ionic compounds and binary molecular compounds.  I use a video for this part; the students watch it as homework.  Identifying Ionic and Molecular Compounds The next day in class I present the kids with a set of cards.  The green cards have the names of a variety of compounds, and the purple cards have the corresponding chemical formulas.  First they sort them into to two piles, and they spread out the set of chemical formulas cards.  I ask my student to sort them into two groups:  ionic compounds and binary molecular compounds (there are only four of the molecular and 12 of the ionic compounds).  Once they have sorted the stack, I tell them to find the correct name to go with each compound.  This is pretty easy for them because all the compounds have different elements or polyatomic ions (pais).  (They have a list of common pais on the back of their periodic table for quick reference.)   Once we have all the names and compounds correctly matched, we look for patterns in the names.  I ask the kids questions like "What do all the molecular compounds have in the names that make them different from the ionics?", or "Where are the metals with roman numeral located on the periodic table?" and the classic, "How do you know that a compound contains a pai?"  The light bulbs start to go off over everyones heads as they sort their pairs into groups and begin to see patterns in the nomenclature rules.  We follow up right away with some white board practice to drive the new ideas home.

An example of a compound from the ion cards and ion cut-outs.
Next we have to tackle writing the chemical formula from the names.  This is another tricky lesson to teach because there are so many pieces of information to evaluate with each compound the kids encounter.  Once again I turn to my cards for help.  This time I start with a set of  ion cards.  I made up cards with a wide range of cations and anions in the set.  To go along with the ions, I also have a set of ion cut-outs that the students can use as a visual aid to help derive the chemical formula of ionic compounds.  I ask my students to make a stack of cations and a stack of anions.  They draw a card from each pile and put them at the top of their white board.  Next they find the shapes that represent these two ions.  Using the shapes, they determine what ratio of cations and anions is necessary for create a neutral compound.  The final step is to write the correct chemical formula.  They also practice naming the compounds as they work through the cards, just to keep that skill fresh in their minds.  I tried to include every kind of ion that they would encounter:  ammonium, multivalent, pais, and main group elements.  Once the make it through the stack, they can reshuffle and have a whole new set of compounds to write.

A heated round of the Nomenclature Card Game.
The final piece of the nomenclature puzzle is writing the chemical formula from the name.  I have one more card game for this part of the lesson.  This time I use a card game that I made up that requires the students to recognize if a name represents part of an ionic compound or a molecular compound.  The cards in the deck have one half of the name of a compound.  For example, a card might read "nitrate" or "dioxide", or "carbon".  The students get five cards in their hand.  On their turn, they flip over the top card in the deck.  Let's say that card says "sodium".  The student has to make a complete (and correct) compound name by using a card in their hand.  Sodium is the first half of an ionic compound, so the student must put down a card with the name of an anion.  You can score a point by making a complete compound name using a card in your hand.  The second point comes from writing the correct chemical formula for the compound you made.  If you get the chemical formula wrong, another player can steal this point if they can write it correctly.  I give the winner of each group a prize from the coveted prize beaker.

Cation Cards
My progression of matching cards, ions cards, and the nomenclature card game have helped to make nomenclature a lively unit in my classroom that I enjoy teaching.

Anion Cards
I have a set of acid cards too to teach the kids how to name acids.  I throw that in the mix too.  The cards are especially helpful with acids because the naming rules are so different than the other compounds the learn.
Names and Chemical Formulas Cards

The acid names and chemical formula cards.

1 comment:

  1. Hello! Wondering what you used as templates for the cations and anions? I absolutely love this idea and I am just about to start teaching this concept and I think it would really help my students understand it better!