Question

An element x has mass number 35 and the number of neutros os 18 .identify the group number and. Period of x

Answer 1

Mass number = Atomic number + no. of neutrons
Atomic number = Mass number - no. of neutrons
= 35-18 = 17
Electronic configuration = 2,8,7
Group no- 17
(Valence electrons 7 means group = 10+7 = 17)
Period - 3
(Electronic configuration shows 3 shells means period 3)