. Answer the following questions associated with these elements, giving reason in each case

The  elements 4Be, 12Mg  and  20Ca, each  having two  valence electrons in  their valence shells, are in periods 2, 3 and  4 respectively of  the  modern periodic table

(a)  In which group should they be?

(b)  Which one of them is least reactive?

(c) Which one of them has take largest atomic size?


Best Answer

Ans. 4Be, 12Mg, 20Ca

          K        L        M       N

4Be     2,       2

12Mg    2,       8,       2

20Ca    2,       8,       8,       2

(a) They all belong to 2nd group of the periodic table as all the elements have two valence electrons in their valence shell.

(b) Be is least reactive as it contains the least number of shells (i.e., 2). The tendency of an atom  to lose electrons on moving down. in a group increases as valence electrons move more and more away from the nucleus and nuclear charge on -valence electrons decreases.

(c) Ca has the largest atomic size as it has the maximum number of shells.


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