Question

17. Out of the 2 elements X ( Z=18)and Y(Z=20), which has bigger atomic radius?
and why?​

Answer 1

Explanation:

Y(Z=20)has bigger atomic radius

Answer 2

Y (Z=20) has a bigger atomic radius.

X (Z=18)

• The atomic number of X is 18.
• Electronic configuration is 2,8,8.
• X belongs to period 3.
• X has a stable electronic configuration due to the complete octet.
• X belongs to group 18 ie; it is a noble gas.
• Noble gases have the largest atomic radius in the respective period.

Y(Z=20)

• The atomic number of Y is 20.

• Electronic configuration is 2,8,8,2.
• Y belongs to period 4 of the periodic table.

Variation of atomic radius in the periodic table

1. Down the group:

• Atomic radius increases down the group due to the addition of an extra shell down the group.

   

    2. Across the period:

• Atomic radius decreases on moving from left to right in the period because of the increasing nuclear pull.

Y has an extra shell and belongs to period 4, therefore it has a bigger atomic radius than X.

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