Question

mendeleevs approach included leaving spaces in his table for elements not yet discovered. he guessed these elements properties based on the patterns of traits in the known elements. his hypothesis was later proven true when elements such as germanium, gallium, and scandium were found. each new find fit the anticipated space in the table with the traits he had calculated. today, the periodic table remains a useful tool that highlights the relationships among elements. which choice provides the best summary of the passage? mendeleev created the periodic table in 1869 to organize elements by atomic weight, which refers to the mass of one atom of that particular element. once mendeleev ordered each known element in the table by its atomic weight, other property patterns in the elements became clear. dmitri mendeleev developed the periodic table in 1869 by arranging elements based on atomic weight and their recurring properties. his predictions about the properties of undiscovered elements were confirmed when new elements were identified. in his 1869 chemistry textbook, mendeleev listed elements based on atomic weight, which provided a basic framework that was later refined to include all known elements. he also made predictions about unknown elements. the periodic table, created by dmitri mendeleev in 1869, serves as a fundamental tool that has evolved significantly since its creation. it demonstrates the relationships between elements, reflecting mendeleevs role as the chemist who made the greatest impact of the 1800s.

Explanation:

The passage focuses on Mendeleev creating the periodic table in 1869 by arranging elements based on atomic weight and their recurring properties, and his predictions about undiscovered elements being confirmed. The second option captures all these key points. The first option only mentions organizing by atomic weight and property patterns becoming clear but misses the prediction aspect. The third option mentions a textbook which is not in the original passage. The fourth option adds an unsubstantiated claim about Mendeleev being the chemist with the greatest impact in the 1800s.

Answer:

Dmitri Mendeleev developed the periodic table in 1869 by arranging elements based on atomic weight and their recurring properties. His predictions about the properties of undiscovered elements were confirmed when new elements were identified.