Final answer:
Hans Christian Oersted's discovery of aluminum and Sir Humphrey Davy's discovery of sodium occurred during a period of rapid advancement in Chemistry, which included the development of the periodic table by Dmitri Mendeleev, who predicted the existence of elements like gallium and germanium.
Step-by-step explanation:
The discovery of aluminum in 1825 by Hans Christian Oersted, and the prior discovery of sodium by Sir Humphrey Davy, were part of a period of significant progress in the field of Chemistry during the 1800s. This era saw the development of theoretical foundations through John Dalton's atomic theory and the contributions of Amadeo Avogadro towards a more quantitative understanding of gases. The field of electrochemistry flourished with Davy and Michael Faraday's work, thanks in part to the invention of the battery by Alessandro Volta. Furthermore, the accurate organization of elements became possible through the efforts of Dimitri Mendeleev and Lothar Meyer, who recognized a periodic relationship among the properties of elements, ultimately leading to the creation of the periodic table. Mendeleev went on to predict the existence of then-unknown elements, such as gallium and germanium, which fitted into the periodic table exactly where he had anticipated, offering strong support for his predictions and the periodic table's design.