Periodic Classification of Elements (C10)

An element "X" has mass number 35 and the number of neutrons is 18. Identify the group number and period of "X".

Answer

Atomic number of X = Mass number of X – No. of neutrons

Atomic number of X = 35 - 18 = 17

Electronic configuration = 2, 8, 7

Group number = 17

Period Number = 3