Themes of The Periodic Table include memory, the quest for knowledge, and the similarities between life and chemistry.

Primo Levi explores his memories throughout the book. He goes into a lot of detail to explain things like the Piedmontese Jewish culture, meeting up with a German who worked in the concentration camp where he was imprisoned, or troubleshooting a mixture of paint in a factory where he works. Each chapter contains a separate memory that, together, make up a framework to help readers understand his life and history.

The quest for knowledge is evident in the experiments that Levi performs. For example, in one chapter he's working on formulating a lipstick that doesn't smear off the mouths of people who wear it. In another, he's in a concentration camp making matches to sell at night. Even when his circumstances are grim, Levi continues thirsting for knowledge and using whatever means are at his disposal to obtain it.

Levi uses chemistry to help explain life because, as a chemist, he sees similarities to chemistry everywhere he looks. He opens the book explaining what argon is, how it's inert, and that it's a noble gas. He then says that his ancestors are like argon in some ways. He specifies that he means not that "all of them were materially inert, for that was not granted them." Instead, they were "inert in their inner spirits, inclined to disinterested speculation, witty discourses, elegant, sophisticated, and gratuitous discussion." Chemistry is the filter through which he views things, partially because his interest and absorption in the subject helped him weather the most difficult times in his life.