Question

While developing his periodic table, Dmitri Mendeleev broke his own rule and placed the element tellurium before iodine in the group. He did this even though tellurium's atomic mass was known to be greater than iodine's. In his notes, Mendeleev stated that he expected tellurium to have a lower atomic mass than iodine. However, all measurements continue to show that tellurium has a greater atomic mass than iodine even though tellurium acts like it has a lower atomic mass. What is the most likely reason that Mendeleev placed tellurium before iodine?

Answer 1

The most likely reason that Mendeleev placed tellurium before iodine is Mendeleev observed that tellurium has chemical properties like other elements in its group, and he did not know that neutrons cause the greater atomic mass.

Answer 2

Answer: he used chemical properties instead of atomic mass

Explanation:

Tellurium was placed that way because it's chemical properties. Tellurium was better fit in the category as oxygen and sulphur

The same ways iodine was placed in the same category of fluorine chlorine