Question

Why did Mendeleev leave blank spaces in his version of the periodic table? A. Mendeleev’s periodic table arranged elements in order of increasing atomic mass; spaces were left for elements not having the correct atomic mass. B. Mendeleev’s periodic table arranged elements in groups of similar chemical properties; spaces were left for elements not having a similar chemical property. C. Mendeleev’s periodic table arranged elements in order of increasing atomic mass; it was noticed that chemical properties repeated. D. Mendeleev predicted an element had not been discovered to fit the space.

Answer 1

Mendeleev left blank spaces in his version of the periodic table for elements he predicted would be discovered, based on the periodic trends and properties of known elements.

Step-by-step explanation:

Dmitri Mendeleev, a Russian chemist, created his version of the periodic table by organizing elements by increasing atomic mass. However, he intentionally left blank spaces for undiscovered elements that he predicted would fill those gaps. This insightful approach allowed the inclusion of elements that were not yet known, but could be predicted to exist based on the periodic trends he observed in the properties of the elements that were already discovered. Answer D correctly reflects Mendeleev's reasoning: he believed that the periodicity of the table suggested the existence of elements that would be discovered to fit these gaps, and he made predictions about their properties.

Answer 2

the answer is D

Step-by-step explanation: