Final answer:
Dimitri Mendeleev and Julius Lothar Meyer were pivotal in the development of the modern periodic table. Mendeleev is known for publishing the first recognized version in 1869 and predicting the existence of undiscovered elements.
Step-by-step explanation:
The modern periodic table is an arrangement of the chemical elements in a table, organized by their atomic number, electron configuration, and recurring chemical properties. Two critical scientists who helped develop the periodic table were Dimitri Mendeleev and Julius Lothar Meyer.
Dimitri Mendeleev
Mendeleev, a Russian chemist, published his first version of the periodic table in 1869. He arranged the 63 known elements by atomic mass and recognized that the properties of elements were related to their atomic mass in a 'periodic' way. This enabled him to predict properties of some elements that had not yet been discovered, leaving gaps in his table for them. For his remarkable foresight and his table's ability to predict the properties of new elements, Mendeleev is often credited with the origin of the periodic table as we know it today.
Julius Lothar Meyer
Meyer, a German chemist, also arranged the elements in a way that demonstrated their periodic properties, but his work received less recognition initially. Like Mendeleev, he noticed the periodicity in the properties related to atomic weight, and his table, published after Mendeleev's, included similar features and element groupings as Mendeleev's table. Despite the similarities, Meyer's work contributed significantly to the development of the periodic system by providing further evidence for the periodic law.
Both scientists played pivotal roles in the development of the periodic table. Their work laid the foundation for what is currently one of the most important tools in chemistry, used universally for predicting the behavior of elements and their compounds.