Question

for an element X it is given that atomic number = 17 and mass number equal 35 write the electronic electron configuration of element X find valency what will be the formula of compound formed between X and Y having valency 3.

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Answer 1

Given :

Mass number of element is 35

Number of neutrons= 18

Formula to find number of protons:

Mass number = number of protons + number of neutrons.

35=× +18

×=35 - 18

X=17.

Number of protons =17 and number of electrons also will be 17 as atom is electrically neutral.

Hence Element is chlorine

Electronic configuraton:

1s2 2s2 2p6 3s2 3p5

Group number= 17

Period number =3

Valency =1

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Answer 2

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,

1. In an electrically neutral atom, the number of protons = number of electrons
2. Mass number = Number of protons + number of neutrons
3. 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