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Question
Why does the size of the atoms progressively become smaller when we move from sodium (Na) to chlorine (Cl) in the third period of the periodic table?
Solution
The size of atoms decreases progressively, on moving from sodium (Na) to chlorine (Cl) in the third period because the atomic number of the elements increases. Likewise, the number of electrons and protons in the atoms also increases. As the positive charges on the nucleus increase, the outermost electrons are held more tightly by the nucleus. Therefore, the size of the atom decreases.
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