Periodic table

The periodic table or Table of Elements was a means of grouping chemical elements. Using the table, many elements share a common atomic weight or symbol, and some even have multiple atomic weights or symbols and are listed twice.

On October 23, 2032, Lieutenant John Kelly recorded that they need to make room on the periodic table, after analyzing the contents of a graviton ellipse. Additionally, Spock stated, in 2269, that the matter-energy cloud had "elements not known in our periodic tables". 

A Table of Elements was seen in a classroom aboard the USS Enterprise (NCC-1701-D) and also in the classroom on Deep Space 9's Promenade. 

Background
This table appeared in. It contains many in-jokes and errors, and is missing several key elements. Elements are also sorted by "atomic weight," and the atomic weights of the known elements differ from their actual atomic weights. One explanation is that with the discovery of subspace, chemistry underwent a revolution to translate the subspace properties of elements. It is also interesting to note that the size of the atom itself (as seen in the Okudagram of the Table of Elements) does not affect the atomic weight. This can be seen with the element Poi, the heaviest element, and that its physical atomic size is much smaller than that of the element Hawkeye, which is much lighter in terms of atomic weight.

The table from "Rascals" was later used for the classroom scenes on Star Trek: Deep Space Nine. However, in at least one case, in the episode (see image on right), the table had a different color code. It is unknown if this table was also labeled with different elements than those seen in "Rascals". Another version of the Periodic Table can be found in the "Starfleet Medical Reference Manual" which is devoid of the "in jokes" found on the Next Generation version.

This is the periodic table used today, with links to real-world elements mentioned in Star Trek: