How is today's periodic table different from the one that Mendeleev published?

Which element is placed in the same period as ruthenium but has a higher atomic number than it?

The symbol for xenon (Xe) would be a part of the noble gas notation for the element.

What is the atomic symbol for the element in group 4B (4) and the fourth period?

After Mendeleev organized the periodic table by atomic weight, he noticed a pattern of ....?

A russian chemist developed the periodic table as a way to group elements and atoms according to

Identify the chemical symbols for the elements carbon, aluminum, hydrogen, oxygen, and sodium.