A scientist who grouped elements based on their properties, regardless of their atomic weight

The scientist you are referring to is Dmitri Mendeleev. He is best known for developing the Periodic Table of Elements. Mendeleev organized elements by their chemical properties and patterns of reactivity rather than solely by atomic weight. This groundbreaking approach allowed him to predict the existence and properties of elements that had not yet been discovered. His arrangement of elements highlighted the periodicity of element properties, laying the foundation for the modern periodic table, which is now organized by atomic number rather than atomic weight. Mendeleev's work was pivotal in advancing the field of chemistry and understanding the relationships between different elements.