How many elements did Mendeleev's periodic table contain?
Mendeleev's periodic table
Therefore, Mendeleev's periodic table has 63 elements.
(a) On what basis did Mendeleev arrange the elements in his periodic table?
(b) On what basis are they arranged now?
How many elements were known when Mendeleev gave his periodic table?
The second and third period of the modern periodic table contains how many elements?