Question

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Answer 1

Answer:

The number of valence electrons increases from 1 to 8 in going from left to right in a period. Thus, the valency increase first from 1 to 4 and then decreases from 4 to 0 while going from left to right along a period in the modern periodic table

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Answer 2

Answer:

(a) (i). Valency of an element is a measure of its combining power with other atoms when it forms chemical compounds or molecules.

   

     (ii). Atomic size is determined by the atomic radius. For an isolated atom, its atomic radius is the distance between the center of the atom (i.e. center of its nucleus) and its outermost shell.

(b). The atomic radius decreases across a period while going left to right due to increase in nuclear charge.

The number of valence electrons increases from 1 to 8 in going from left to right in a period. Thus, the valency increase first from 1 to 4 and then decreases from 4 to 0 while going from left to right along a period in the modern periodic table.