(a) What is the main characteristic of the last elements in the periods of the periodic table? What is the general name of such elements?
(b) What is the number of elements in: (a) 1st period, and (b) 3rd period, of the modern periodic table?

Academic Chemistry NCERT Class 10

(a) The main characteristic of the last elements in the periods of the periodic table is that they all have 8 valence electrons in their atoms except helium. Such elements are known as noble gases that have a stable electronic configuration.

(b) The number of elements in:

(i) The first period = 2.

(ii) The 3rd period= 8.

Simply Easy Learning

Updated on: 10-Oct-2022

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