Question

As we go from left to right side within a period , the atomic radius decreases.
Explain with the help of the periodic table.

Answer 1

Atomic radius decreases as we go from left to right in a period. We can ascribe it to increase in nuclear charge which tends to pull the electron closer to the nucleus so that the size of the atom is reduced.

for ex- the atomic radii of the elements in the first group are

Na     Li            Rb      Cs        K

186   152       244      262     231

the elements can be arranged in increasing order of their atomic radii

                  Li<Na<K<Rb<Cs

Answer 2

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on moving from left to right side in a period of periodic table the size of atoms decreases ..

since the size of atom is represented by its atomic radius we can also say that on moving from left to right in a period of periodic table atomic radius of elements decreases ..

does in the table given above sodium is the biggest atom having atomic radius of 186 picometre whereas chlorine atom is a smallest atom having any radius of 99 picometres ..

does as we move from sodium two chlorine in third period the size of atoms of element decreases so in third period shown above sodium atom is the biggest whereas fluorine atom is the smallest in size

EXPLANATION :-

as we move from left to right in a period the atomic number of elements increases which means that the number of protons and electrons in atoms increases so that's electrons being added to the same shell ..

*****therefore in any period the alkali metal atom like Sodium, Potassium exetra which is place at the extreme left side in the periodic table is smallest size ..

NOTE :- however about the size of atom of an inert gas is bigger than that of proceeding halogen atom because of structural stability of its outermost shell consisting of an octet of electrons ..