Question

In Mendeleev's Periodic Table, why was there no mention of noble gases like Helium, Neon And Argon?

Answer 1

Mendeleev's Periodic table:

• Dmitri Ivanovich Mendeleev (Russian chemist) has an important role in the early development of the periodic table.
• He is known as the father of the modern periodic table.
• The elements in the Mendeleev periodic table are arranged on the basis of their fundamental properties i.e. atomic mass, and chemical properties.
• His periodic law states that “The properties of elements are the periodic function of their atomic masses.”

Reason for not mentioning Noble gas in Mendeleev's Periodic Table:

• In the Mendeleev periodic table, there was no mention of noble gases like helium$\left(\mathrm{He}\right)$, neon$\left(\mathrm{Ne}\right)$, and argon$\left(\mathrm{Ar}\right)$.
• This is because they were not known at that time and were discovered much later.
• Since they are very inert gases they are present in extremely low concentrations in the atmosphere, so it was difficult to detect them with primitive technology.