Answer:

Given:

Atomic number of element x = 17

Mass number of element x = 35

To find:

Electronic configuration of element x

Find the valency of element x

The formula of the compound formed between X and Y( having valency 3)

Solution:

We know that,

In an electrically neutral atom, the number of protons = number of electrons

Mass number = Number of protons + number of neutrons

Atomic number = Number of protons

So, for the element x:

Atomic number = Number of protons = 17

Number of protons = Number of electrons = 17

Mass number = Number of protons + number of neutrons

35 = 17 + number of neutrons

Number of neutrons = 35 - 17 = 18

Thus, the element x is chlorine ( atomic number = 17)

Electronic configuration of element x (Cl) = 1s²2s²2p⁶3s²3p⁵

Valency of element x (Cl) = 8-7 = 1

The formula of the compound formed between X and Y( having valency 3) = X₃Y

Explanation: