Question

An element 'X' has mass number 35 and number of neutrons 18. What will be the atomic number and electronic configuration of 'X'. Also mention the group number, period number and valency of 'X'. ​

Answer 1

mass no. = no. of protons + no. of neutrons in the atom

35 = x + 18

x = 17

no. of protons = atomic no. = 17

configuration => 2 8 7

group no. =17

period = 3rd

valency = 1

Answer 2

X-argon

K L M

2 8 8

18th group - (inertgas)

3rd period