What were the important contributions of Mendeleev's periodic table?

(N/A) Mendeleev's periodic table was one of the greatest achievements in the development of chemistry. Some of the important contributions are:
$(A)$ Systematic study of the elements:
- It simplified the study of the chemistry of elements.
- Knowing the properties of one element in a group,the properties of other elements in the same group could be easily predicted.
- This made it very useful for studying and remembering the properties of a large number of elements.
$(B)$ Correction of atomic mass:
- It helped in correcting the atomic masses of some elements based on their positions in the table.
- For example,the atomic mass of beryllium was corrected from $13.5$ to $9$.
- Similarly,the atomic masses of indium,gold,platinum,etc.,were corrected.
$(C)$ Prediction of new elements:
- At the time of Mendeleev,only $56$ elements were known.
- While arranging these elements,he left gaps for undiscovered elements.
- He predicted the properties of these elements based on their positions.
- The observed properties of these elements,when discovered later,were found to be similar to those predicted by Mendeleev.

$Group/Element$	$Atomic$ $weight/Note$
$VI$. Tellurium	$127.6$. Higher atomic weight
$VII$. Iodine	$126.4$. Lower atomic weight