Describe briefly Mendeleev's periodic table along
with its merits.

Explanation

To give the proper place in the periodic table, atomic masses, of some elements wre revised in accordance with their properties. For examples, the peviously determined atomic mass of beryllium , 14.09, was changed to the correct value, 9.4 , and beryllium was placed before boron.
(2) Mendeleev had kept some vacant places in the periodic table for elements that were yet to be discovered . Three of these unknown elements were given the names eka-boron, eka- aluminium and eka-silicon from the known neighbours and their atomic masses were indicated as 44,68 and 72 , respectively. Their properties were also, predicted. Later on these elements were discovered subsequently, and were named as scandium (SC), gallium (Ga) and germanium (Ge) respectively. The properties of these elements matched well with those predicted by Mendeleev. Due to this success all were convinced about the importance of Mendeleev's Periodic table.
(3) There was no place reserved for noble gases in Mendeleev's original periodic table. When noble gases such as helium , neon and argon were discovered, Mendeleev created the zero group' without disturbing the original periodic table in which the noble gases were placed very well.