Periodic Pasta Table
Create a three-dimensional model of the periodic table using sticks of spaghetti and see the trends in atomic properties that underlie the arrangement of elements into periods and families.
- Printed copy of the periodic table (download here)
(Source: Lawrence Berkeley National Laboratory)
- Glue stick
- Two pieces of 8 1/2 inch x 11 inch (A4) corrugated cardboard (Styrofoam or foamcore will work, too)
- One sheet of 8 1/2 inch x 11 inch (A4) scrap paper
- Geometry compass with a sharp point or a nail about the diameter of a spaghetti strand (to make holes in the paper and cardboard)
- Dry spaghetti (one package)
- Metric ruler
- Optional: calculator, transparent tape
- Using the glue stick, glue the two pieces of cardboard together to make a thicker piece (see photo below). Then glue the printed-out periodic table on top of the cardboard.
- Use the compass point (or other sharp implement) to poke holes through both the printed periodic table and the double cardboard underlayer (see left photo below). You’ll need to punch one hole for each element on the table, and in the same location within each element’s border. (On the periodic table provided, the upper left corner next to each symbol works well. Click to enlarge the right photo below) As you work, make sure to punch the holes straight up and down so your pasta sticks won’t tilt when inserted. (Note: It may be easier to poke holes in the cardboard if you lay the periodic table/cardboard sandwich over the edge of a table.)
- After you’ve poked a hole by each element, glue a sheet of scrap paper to the backside of the cardboard stack to prevent your spaghetti sticks from slipping through (see photo below).
Start by choosing one atomic property to scale and plot. For instance, you might choose atomic radius, ionization energy, electron affinity, electronegativity, density, melting point, boiling point, etc. For our example, we’ve used the calculated atomic radius of elements.
(Note: Depending on the property you want to plot, you may need to find a table or chart that has your chosen data. A sampling of resources can be found in the Resources section below.)
Once you’ve found a table to work from, analyze the information available and decide on a method to scale your data so it can be converted into an appropriate length of spaghetti. (A piece of spaghetti is usually about 25 cm long.) Note that your data might be in units not usually associated with standard lengths—for example, kilojoules per mole, electron volts, picometers, or even no units, such as for electronegativity.
Calculate the scaled length for each spaghetti stick to be used (a calculator might be helpful), and then measure and break spaghetti pieces into appropriate lengths to represent the relative scaled property of each element (see photo below). If a few of your spaghetti sticks need to be longer than 25cm, just tape an extra piece to the end to make up the difference. If more than a few need extensions, change your conversion method for scaling your strands.
In our example, we did this by creating a table of atomic radii in picometers (pm) that we scaled to centimeters (cm). This represents a 1010 times increase in length, since 1 pm is 10-12 meters and 1 cm is 10-10 meters. A simple way to make this conversion mathematically is to divide each value by 10, and then let centimeters stand for picometers. The table below, showing data for the elements lithium to neon, is a sample of the calculations we used to find the lengths of the sticks of spaghetti we needed for our table.
When you’ve measured each piece of spaghetti needed, insert each stick of spaghetti into the appropriate punched hole in your cardboard periodic table (see photo below). Look at the pattern and shape of your table of spaghetti. Can you pick out any trends? How do the rows and columns compare?
In building this three-dimensional model, you’ve created the rows, known as periods, and columns, known as families, of an elemental bar graph that you can visually scan for patterns. Looking at the landscape of spaghetti sticks shows you how elemental properties change (or don’t) as you go right, left, or up and down the periodic table. It is these patterns that make the periodic table so useful. They give deep insight into the internal workings of different elements, both explaining and predicting how they will interact with other atoms. These patterns define our universe, and even our very existence. Some general trends of atomic properties are shown in the figure below.
Periodic Trends image source: Mirek2 [CC0], from Wikimedia Commons
Make several different three-dimensional periodic tables of several different properties to compare. Do you notice any relationships between the models? Click to enlarge the photos below to see examples for electronegativity (left) and atomic radius (right).
Try using different types of spaghetti for different types of elements. For example, black squid-ink pasta could be used to show the noble gasses, green spinach pasta could show non-metals, and brown whole wheat pasta can represent the metalloids.
One way to start this project is to assign students to a period (row) or a family (column) of elements to plot. Combining the periods or families will produce a full table.
Spaghetti is inexpensive and easily replaced, but if you want something a little more durable, try other materials for your graphs, such as coffee stirrers, drinking straws, or skewers.