Question

Write the merits of the modern periodic table over Mendeleev's Periodic table.

Answer 1

Advantages Of Modern Periodic Table Over Mendeleev's Table:

• The classification of elements is based on the atomic number, which is a more fundamental property.
  
• The position of Isotopes-
  

Since all isotopes of an element have the same number of protons, their atomic number is also the same.

And since all isotopes of an element have the same atomic number, they can be put at the same position in the periodic table.

• The position of Argon and Potassium -
  

The atomic number of argon is 18 and its mass number is 40 while the atomic number of Potassium is 19 and its mass number is 39.

Now, according to modern periodic law, elements are arranged in the increasing order of their atomic number.

So argon, with its lower atomic number, should come first, and potassium with its higher atomic number should come later.

• The lanthanides and actinides are placed separately at the bottom of the periodic table.