Periodic Table Accessibility

What Makes a Periodic Table Accessible?

To be fully accessible, a periodic table should be structured so that it is:

Keyboard navigable: students must be able to navigate through the elements without manipulating a mouse.
Screen reader accessible: text must be readable by a screen reader.
Scalable: zooming in should not cause the table to become fuzzy or otherwise difficult to read.
Colorblind friendly: the table should either be readable in grayscale mode or else not rely on color alone to convey information (e.g. element type).

Unfortunately, some of the premade "accessible" periodic tables miss on this last count because their design focuses more narrowly on accessibility for blind individuals rather than all forms of vision impairment.

Choosing an Accessible Periodic Table

Our general recommendation for an accessible Periodic Table is the McGraw Hill Accessible Periodic Table [PDF] . There are two narrow, known pedagogical limitations to this table:

It openly identifies all elements as metals, metalloids, and non-metals.
It labels the columns 1-18, without any separate numbering for main groups.

The first limitation does prevent instructors from directly testing whether or not students know where the metals and non-metals are on the periodic table, but that seems unlikely to be a major issue— a lot of classroom periodic tables give this information away. It does not give away which metals are transition metals, allowing instructors to still easily test students on that information. A bigger issue is that not all classes recognize metalloids as a separate group. However, instructors can easily address this issue by telling students what certain metalloids should be considered for the purposes of their class. This is no different than telling students which transition metals you expect them to memorize as having a fixed charge.

The second limitation can easily be worked around by thoughtful pedagogy (e.g. relating the main groups numbers to the general column numbers early on) and is also true on the official AP Chemistry equation sheet's Periodic Table.

If an instructor needs other information to be present, or considers the limitations above to be unacceptable pedagogically, they are encouraged to search for a solution that meets their needs based on the above guidelines. Perkins School for the Blind: Accessible Periodic Table Options and Veronica with Four Eyes: Accessible Periodic Tables for Low Vision may be good places to start.

Alternatively, if only a small portion of the table is needed, the instructor can recreate that portion of the table as a simple data table. The headings in the data table can be used to make it clear where the equivalent information would be found on a full Periodic Table. For example:

Table 1: Electronegativity Values for Selected Portion of Periodic Table
Location on Periodic Table	Column 13	Column 14	Column 15	Column 16	Column 17
Row 2	B 1.5	C 2.5	N 3.0	O 3.5	F 4.0
Row 3	Al 1.5	Si 1.8	P 2.1	S 2.5	Cl 3.0

Providing a Linearized Table for Low Vision Students

When sharing their lived experiences with others, low vision students often indicate that a simple table or nested list that eschews the complex, 2D visual organization of the periodic table entirely is much easier to use for looking up properties like atomic mass. However, such a table would likely prove inaccessible for individuals with certain cognitive disabilities. For this reason, we recommend including a link out to such a list alongside an accessible version of the visual periodic table to allow students to quickly look up common properties.

To make one that has the right amount of information for your class, we recommend:

Finding a pre-made reference file like this Linearized Virginia SOL Periodic Table (.csv) that includes all of the relevant atomic properties (see Veronica Lake, Veronica With Four Eyes).
Downloading the file to your local computer.
Opening the file and deleting any extra columns that may give away answers (e.g. some files include a column of standard state electron configurations).
If relevant: Converting the file to a format that will usable during an exam given software restrictions (e.g. an html document).
Uploading the modified file to your course and linking to it in your equation sheet.

Like the visual periodic table itself, this version should also be available to students ahead of time so that individuals can familiarize themselves with it and practice as needed.

Explaining the Periodic Table Accessibly

It is important to realize that an accessible version of the periodic table is only useful if students are able to correctly associate the professor's explanations with the table. This means that:

Students should be provided with directions on how to access the accessible periodic table as early as possible in the course.
Professors need to be specific in their verbal descriptions when referencing the periodic table

This second point is particularly important for lecture video recordings, even if accessible lecture note handouts are provided. The following are some examples of how common explanations could be made accessible.

When describing the location of the alkali metals:

Inaccessible: "this column here"
Improved: "the first column"
Clearest: "the first column on the left, except for hydrogen on the top"

When describing the boundary between metals and non-metals:

Inaccessible: "this black line separates the metals from the nonmetals"
Improved:"this line starting between boron and aluminum and forming a downwards stairstep separates the metals from the nonmetals"
Clearest: "a right and down stairstep pattern starting below boron and above aluminum separates the metals from the nonmetals. [Clarify what metalloids count as]"

When introducing the $H O B r F I N C l$ elements:

Inaccessible: "hydrogen here, and these six elements that form the shape of a seven here, exist as diatomic molecules"
Improved:"hydrogen, [pause] nitrogen, oxygen, fluorine, chlorine, bromine, and iodine exist as diatomic molecules. You can remember them because on the periodic table, the six besides hydrogen form the shape of a seven."
More Improved: "Seven elements — hydrogen, [pause] nitrogen, oxygen, fluorine, chlorine, bromine, and iodine exist as diatomic molecules. You can remember them because nitrogen right to fluorine, down to iodine on the periodic table form the shape of a seven, so it's those six plus hydrogen.""

Note that on the last example, there is nothing wrong with sharing the memorization device that there are seven elements and they form the shape of a seven (a visual trick)! Accessibility only becomes an issue when an instructor leads with that description, assuming that all students can see where they are tracing.

Embedding the Periodic Table

When referring to the periodic table inside another document, such as a PowerPoint of lecture slides, it would be both impractical for the instructor and unhelpful for the students to try and embed a fully AT-interactive periodic table every time.

Instead, all students should be provided with the fully accessible version of the Periodic Table that you have chosen for your class as early on as possible so that they can follow along using it during lectures. One possibility is to provide it as a required text within the course syllabus or course information page. If you are teaching a course that introduces the periodic table, like Chem 101 or 102, consider also linking to it directly before your introductory lecture on the topic.

Once an appropriate, accessible periodic table has been provided, a visually accessible image of the periodic table with appropriate alt text and extended description should be sufficient in most documents. If high levels of interactivity are required however, link out to your fully accessible version using a descriptive link in addition. Keep in mind that if the interaction is with a small subset of the full table, embedding an accessible data table as discussed above is also an option.

Below we present some examples of how this might be implemented. The example extended descriptions are collapsible to follow best web-based accessibility practices. In a PowerPoint fiile, these descriptions would be placed in the Speaker Notes section (see our PowerPoint Accessibility Guide).

Note to screen-reader users: There will be repeated alt text and other sub-optimally accessible practices in the example subsections here.

Example 1: Introducing the Periodic Table

A simple introduction to the periodic table. The alt text on the image reads: "The periodic table of elements. Link to accessible version provided below."

Example 2: Introducing Diatomic Elements

A periodic table with seven elements highlighted. — An introduction to the diatomic elements. The alt text on the image reads: "A periodic table with seven elements highlighted"

Example 3: Periodic Table Trends

A common illustration of periodic table trends. The alt text on the image reads: "A periodic table with multiple arrows indicating atomic trends."

Note: If information is already visible and explained fully on a page, it does not need to be repeated in an extended description. For example, if a slide already says "atomic radius increases from right to left and top to bottom" in text you don't need to repeat that in an extended description.

See WebAIM's Accessible Image and WebAIM's Alternative Text for more general information on alt text.