Question

In the periodic table from left to right in a period the atomic volume.
(A) Decrease
(B) Increase
(C) Remains same
(D) First decrease then increase

Answer 1

The volume occupied by a mole of atoms at room temperature is called atomic volume.
The formula to calculate atomic volume is, Atomic volume $= \dfrac{{{\text{atomic weight}}}}{{{\text{density}}}}$
Its units are ${m^3}$ or $c{m^3}$

Complete step by step answer:
Periodic trends of atomic volume across a period firstly decrease from left to right and then increase.
The main role in this trend is played by nuclear charge. Nuclear charge is a positive charge exerted by a nucleus on electrons of the atom. From left to right in a period, the number of shells remains the same. But, the number of electrons, protons and neutrons increases with increase in atomic number.

Due to the increase in the number of protons in the shell, more nuclear charge is exerted on the electrons of that atom. It results in increased nuclear charge per electron and thus it attracts the electrons and holds them tightly. Due to this phenomenon, the volume of an atom goes on decreasing from left to right of the period.

In the extreme right end noble gases are the inert gaseous atoms that have complete atomic orbitals. The volume of noble gases is relatively large because they have large van der waals radii, due to complete. Valence shell and paired electrons. These electrons cause repulsion and lead to increase in volume of the noble gas.

Hence, the correct option is (D) .

Note:
In a given period, the largest atomic volume is of the first group is Alkali metals and the smallest volume is of Group $17$ i.e. halogens. Francium is the element that has the largest atomic volume.