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.