Question

on the basis of EC how will you identify the first and the last element of a period. PLEASE DON'T SPAM IF U DON'T KNOW THE ANSWER THEN PLEASE STAY AWAY​

Answer 1

Answer:

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if the number of valence electron is 1 then the element is said to be the first element of a period if the number of valency electrons are 8 the element is said to be the last element of a period

or

according to the atomic number we get electronic configuration. if we know the atomic number of the first element and the last element we can locate it.

Answer 2

Explanation:

The element will be present in which period will depend on the number of valence electrons of that element. Since number of valence electrons varies from 1 to 8, therefore, the first element present in period 1 will have 1 valence electron and element present in last period will have 8 valence electrons (except in the first period where last element helium has only 2 valence electrons).