Why the best one might be one you design yourself.
If you’re in the market for periodic table, the number of options is dizzying.
What’s the point of having a periodic table in your classroom? Should you choose one that shows elements’ properties? Has pretty pictures? Is color coded?
Which to choose? For our classroom, the answer was none of the above.
This wasn’t pragmatic, meaning we lacked space or funds—though it’s always a bit of that—I wanted to help students focus on the main point of the table. If there was ever an example of losing the view of the forest by focusing on the trees, this is it! Few of the published tables do this well.
The main point of the periodic table is, in short, its periodicity—the idea that certain features of the elements recur at regular intervals. I find that many of the tables bury this feature by adding many properties of the elements.
Middle school is the first time most students study the table in any depth. How do we help students navigate the task of learning to read the table?
In my classroom, we built our own. More than a craft project or busy work, this was an opportunity to be able to focus on the major components and leave out all the rest.
But what to choose? The possibilities are endless. Google images of the periodic table and you’ll see an abundance of uniquely coded charts.
For us it was all about the periodicity; how could we best see that? What would we choose and what would we leave out? How could we make it useful again and again?
Using pictures
If the purpose of the table is to show the recurring features of the elements, then pretty pictures aren’t going to add much. Plus they might confuse. Do we have these types of posters in our classroom? Absolutely. They’re beautiful and interesting and spark discussions, but they don’t teach us much about the table itself.
Identifying Noble Gases, Halogens, etc.
Many periodic tables color code these and other families. This adds a level of detail that’s unnecessary and can confuse or clutter the table, and so we forgo this as well. Not that we don’t discuss the families, but we give them a pretty light touch.
Lewis Diagrams
Could we use Lewis diagrams? We could. They would show us the outer arrangement of electrons and allow us to see how elements in a particular group or family (vertical column) share this feature. So that’s a contender.
Bohr Diagrams
Could we add these? We could. These start to become complicated after number 18, Argon, in that Bohr diagrams don’t follow simple rules after that point. There is still a pattern, though, albeit a complicated one. It can also be challenging to find information that students need to complete these diagrams. If we choose to do this, we’ll have to furnish them with that info.
Even with its limitations, this is my favorite. You can see why elements are in certain groups AND periods. Once you understand that electron arrangement determines properties of elements, you can start to see why they’re grouped the way they are.
Electron, Proton, Neutron arrangement
We’ve also added this, though it’s in small, non-distracting writing. You can use these numbers to trace the pattern of protons and electrons (and less so neutrons) through the sequence.
Solids, Liquid, Gasses
I’m not sure how crucial this info is, tho it can be helpful to see how the solids are on the left and the gasses are on the right. You can see that most gases are towards the top of the table. You could have some good discussions about why this was so and discuss how a heavy element like Xenon remains a gas. We use a simple color coding and not a picture-based key which can clutter.
Metals, Nonmetals, and Metalloids
The table has a pattern of metals on the left and nonmetals on the right with metalloids between them. Similar to the previous discussion, this gives us additional talking points and allows us to see another of the trends in the table. Not everyone agrees on which elements are metalloids and so that can affect how you code your table. This discussion also gets us talking about how we can disagree as scientists.
OTHER CHOICES
Color Coding
Color coding simplifies. And complicates. If you’re not careful, you can confuse students with too much coding. We chose two sets of coding which might be one too many!! Currently, ours looks like this:
The color of the text:
Red--Gases
Green--Liquids
Black--Solids
The color of Shading:
Yellow-- nonmetals
Orange--metalloids
Blue--Metals
Keep in mind that color coding only helps those who can see color. About 10% of the boys in your classroom will have some form of colorblindness—and may or may not divulge that info to you!
Add symbols
You’ll have to make some choices… too many will confuse. We add small symbols to show radioactive and synthetic elements. Those marked radioactive have no known stable isotopes (since most elements have radioactive isotopes we don’t code for those). In this way, we can see that most radioactive elements are at the bottom of the chart. This is more obvious if you build the extended table as described below.
Those marked synthetic have no natural isotopes. This blew my mind when I first learned it in school… that some elements only exist inside a lab. Knowing the periodic table as we do, some of today’s elements were predicted long before they were discovered or isolated.
Mendeleev gets credit for inventing the table as we now use it even though there were prior versions to his, and the one we use now has changed significantly. But the concept that he realized—the repetition of the elements’ properties—was his genius. He was also able to predict properties of elements not yet discovered.
OTHER BENEFITS
No Limits
Most periodic tables have two orphaned rows at the bottom. As a kid, I thought these were less important since we never referred to them. I was always confused about why they were there… a subtext, an asterisk? Sometimes there was a line connecting them to the main table; sometimes there wasn’t. It took me a long time to realize that they’re not placed there for scientific or even educational reasons, but rather it keeps the poster a manageable size.
In its natural state, the table is incredibly wide and unwieldy. But building the table yourself allows you to place the elements accurately. This was enlightening the first time I saw a table arranged like this and I’ve never taken the Lanthanides for granted since!
No Space? Make a Card Sort
If you don’t have the space to display your table, consider using it as a card sort. Once all the cards are made, kids can lay them out on a table or the floor to look for the patterns before returning them to a small stack. Not only does this save space, it acts as a learning activity each time kids lay them out. This type of engagement— handling and sorting cards— can be vital for some learners and helpful for most.