[2026] PTE Academic Listening - Fill in the Blanks (Type In)

The development of the modern periodic table was a landmark in the history of chemistry. Dmitri Mendeleev organized the known elements based on their atomic and chemical properties. He famously left in the table for elements that had not yet been discovered, predicting their existence with remarkable accuracy. As new elements were found, the table was refined to reflect our growing understanding of atomic . Today, the arrangement of elements is determined by their atomic rather than their weight. This universal remains an essential tool for scientists to understand the fundamental building blocks of the universe.