. Define the following terms


(a)  Define the following terms: 

 

(i) Valency; (ii) Atomic  size

 

(b) How do the valency and' the atomic  size of the elements vary while going from  left to right along a period in  the modern periodic table

 

Best Answer

(a) (i) Valency. The combining capacity of an element is called its valency.

 

• The valency of an element is determined by the number of valence  electrons present  in the atom  of the element.

 

• The number of electrons lost or gained or shared by one atom of an element to achieve  the nearest  inert gas configuration gives the valency  of the element.

 

(ii) Atomic size. The atomic size of an atom is the distance  between the centre of the

 

nucleus and  outermost electron  shell of an isolated  atom.

 

(b)  - On moving from  left to right  along  a period  in the modem periodic  table, the valency  of elements increases  from 1 to 4 and  then  decreases to zero.

 

- On moving  from  left to right  in a period  of the  periodic  table,  the size  of the atoms  decreases

 

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