Question

10 points

Answer 1

In 1869 he published a table of the elements organized by increasing atomic mass.

Mendeleev is called the "father of the modern periodic table

stated that if the atomic weight of an element caused it to be placed in the wrong group, then the weight must be wrong. (He corrected the atomic masses of Be, In, and U)

was so confident in his table that he used it to predict the physical properties of three elements that were yet unknown.

After the discovery of these unknown elements between 1874 and 1885, and the fact that Mendeleev's predictions for Sc, Ga, and Ge were amazingly close to the actual values, his table was generally accepted.

However, in spite of Mendeleev's great achievement, problems arose when new elements were discovered and more accurate atomic weights determined.

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Answer 2

Problem Mendeleev encountered was that sometimes the next heaviest element in his list did not fit the properties of the next available place on the table. He would skip places on the table, leaving holes, in order to put the element in a group with elements with similar properties.