Question

An element X has mass number 35 and number of neutrons 18. Write atomic number, number of protons and electronic configuration of 'X'. Also write valency of 'X. ​

Answer 1

Answer:

As per formula

NO. of neutrons = atomic mass + numbers of proton

35 = 18 + number of protons

35-18=17

NO. of protons = 17

No. of electrons = 17

Atomic no. of X = 17

So,

electronic configuration of X = 2,8,7

valency of X = 8-7 = 1^-

Element X is chlorine and member of group 3 and period 3

Answer 2

Explanation:

Atomic number of X = Mass number of X - Number of neutrons =35-18=17

Therefore, electronic configuration of X = 2, 8, 7

Group number = 17

Period number = 3

Valency=8-7=1