An element ‘X’ belong to 3rd period and group13 of the Modern Periodic Table. (a) Determine the valence electrons and the valency of ‘X’. (b) Molecular formula of the compound formed when ‘X’ reacts with an element ‘Y’(atomic number = 8). (c) Write the name and formula of the compound formed when ‘X’ combines with chlorine.

 

Answer

1. Group Number = 10 + Number of electrons in outermost shell(valence electrons)

So, Number of valence electrons  = 13 - 10 = 3

Therefore, Valency = 3.  

2. Atomic number of Y = 8

Electronic configuration of Y: 2 , 6 

It has a tendency to gain 2 electrons to become stable i.e. its valency is 2.

Valency of X = 3

Valency of Y = 2

Reaction of X with Y - Teachoo.jpg

The compound they will form is X 2 Y 3 .

3. Chlorine has a valency of -1  

X has a valency of 3.

Reaction of X with Cl - Teachoo.jpg

The compound they will form is XCl 3 .

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CA Maninder Singh is a Chartered Accountant for the past 13 years and a teacher from the past 17 years. He teaches Science, Economics, Accounting and English at Teachoo