This thesis demonstrates how three chemists–Dmitrii Ivanovich Mendeleev, Julius Lothar Meyer, and John Newlands–emphasised different values when developing their systematisations of the chemical elements in 1863-1875. While no chemist emphasised just one value in the course of establishing of their systematisations, I argue that Newlands elevated simplicity (“simple relation”), Mendeleev completeness (polnost’), and Meyer carefulness when systematising the elements. This thesis sets to show that values provide an illuminating framework to articulate the differences among the competing periodic systems, and give us a novel reading of the priority dispute concerning the discovery of the periodic system.