Which elements were at the peaks of the Lothar Meyer curve?

Fill in the blanks given below:
$(i)$ The first scientist to think about the properties of elements was ......... .
$(ii)$ The relationship of properties of elements suggested by Dobereiner is known as ........... .
$(iii)$ The Law of Octaves was proposed by the chemist ......... .
$(iv)$ The first periodic table was constructed by .......... and .......... .

Briefly describe the contributions of various scientists to the development of the Periodic Table.

Which of the following is a Dobereiner's triad?

What is the importance of the Periodic Table?

Explain the "Law of Triads" with examples.