Pattern in the Elements

Question 1

In 1869, the Russian scientist Dmitri Mendeleev discovered a set of patterns in the properties of the elements. He noticed that a pattern of properties appeared when he arranged the elements in order of…

Answer 1

increasing atomic mass.

Question 2

What is the atomic mass of an element?

Answer 2

the average mass of all the isotopes of that element.

Question 3

In the periodic table, the properties of the elements…

Answer 3

repeat in each period, or row, of the table.

Question 4

Mendeleev left three blank spaces in the table. What did Mendeleev predict about those three spaces?

Answer 4

He predicted that they would be filled with elements that had not yet been discovered and he predicted the properties of those elements.

Question 5

What ended being the result of Mendeleev’s prediction?

Answer 5

Those elements were discovered and their properties were close to what Mendeleev predicted.