Question

(a) Two elements X and Y have atomic numbers 12 and 17
respectively.
i) Find their valencies.
ii) Calculate the total number of electrons in their lons

Answer 1

Explanation:

we have two elements of atomic number 12 and 17.

that is X is magnesium and Y is chlorine.

since valency of magnesium is 2 and valency of chlorine is 1.

Answer 2

Answer:

element having atomic number 12 is magnesium and 17 is chlorine.

1. electronic configuration of Mg is: 2,8,2

so, Mg lost 2 electron to get stable. valency is +2.

electronic configuration of Cl is: 2,8,8,1

so, Cl lost 1 electron to get stable. valency is -1.

2. no. of electrons= atomic number of element

No. of electron in Mg and Cl is 12 and 17 respectively.

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