The theme surrounding scientific discoveries is quite neglected in and about the sciences, especially in terms of historical and epistemological understanding. Discoveries are often treated as simple information about dates, places, and people. This work presents discussions centered on historical episodes related to chemical elements and the Periodic Law, based on reflections by Thomas Kuhn and Norwood Hanson, aiming to highlight and contextualize specific scientific discoveries' conceptual and epistemological structure. With that in mind, issues related to the inseparability of the (...) contexts of discovery and justification are recovered, along with the complex intrinsic structures of the genesis of scientific knowledge and distinct types and categories of scientific discoveries. (shrink)