. An element X belongs to 3rd period and group 17 of the periodic table

State  its  (i) electronic  configuration, (ii) valency. Justify  your answer  with  reasoning



Best Answer

Ans. (i) Electronic configuration. 'X' has three energy shells-K, L, M (as it belongs to the 3rd

period and the period number of an element is equal to the number of shells in its atom).

'X' has 7 valence electrons since the group  number of an element having more than 2 valence electrons is equal to the valence electrons plus 10.


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