. 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

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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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