The aim of this essay is to examine the iconic nature of Mendeleev's periodic table in light of the philosophy of the American pragmatist Charles Sanders Peirce. Mendeleev and Peirce lived at approximately the same time during the 19th and early 20th centuries. They both trained as chemists and, in 1869, the year of Mendeleev's first arrangement of the chemical elements, Peirce published his own arrangement, also based on atomic weights. Peirce developed a theory of iconicity as part of his wider semiotics, an important characteristic of an icon being its epistemic fruitfulness. The periodic table proved to be epistemically fruitful in predicting new relations—new knowledge—such as revised atomic weights and novel elements. By viewing the periodic table through the lens of Peirce's iconicity, I will show how Mendeleev was able both to reveal and to make perspicuous the relations between the chemical elements.