Question

An element 'X' has mass number 35 and neutrons 18. Write atomic number, electronic configuration, group number , period number and valency ?

Answer 1

chlorine 35

atomic number 17

electronic configration { 2,8,7 }

group no. 17

period no. 3

valency 1 since this element is in the halogen family.

chlorine 35 and chlorine 37 are isotops.

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Answer 2

35-18=17

so the electrons are 17 hence the electronic configuration is 2.8.7 and valency 1