Question

For a given Period, which is the smallest atom?

Answer 1

A row of chemical elements in the periodic chart is called a period. The number of electron shells in each element in a row is the same. Each subsequent element in a period has one more proton than its predecessor and is less metallic. The periodic rule is reflected in this arrangement, as groupings of elements in the same column have comparable chemical and physical characteristics.

Complete answer:
A chemical element's atomic radius is a measurement of the size of its atoms, generally the mean or normal distance between the nucleus's centre and the border of the surrounding electron shells. There are numerous non-equivalent definitions of atomic radius since the border is not a well-defined physical object. Van der Waals radius, ionic radius, metallic radius, and covalent radius are four commonly used definitions of atomic radius. Typically, atomic radius is measured in a bound form because of the difficulties of isolating atoms to measure their radii individually; nevertheless, theoretical calculations are much easier when considering atoms in isolation.
In fact, the inert gases are the SMALLEST atoms in their Periods. As we move our gaze over the Period from right to left, atomic size DECREASES and INCREASES along a Group, a column of the Periodic Table.
The electrical structure causes the periodic drop. Incomplete electron shells are inefficient at shielding the nuclear charge. Throughout the Period, Z dominates, i.e. nuclear charge dominates. Shielding by other electrons wins down a Group, and atomic radii rise dramatically.
As the z-effective increases, the atomic radius falls as the period progresses from left to right. Halogens have the lowest radius in a period as a result. Because they have Van der Waals radii, noble gases have the greatest atomic radii. The atomic radius of noble gas atoms, like atoms in other groups, increases gradually from one period to the next as the number of electrons increases. The size of an atom is linked to a number of characteristics.
Hence Noble gases Is the right answer.

Note:
The noble gases are members of group 18 for the first six periods of the periodic table. Except under the most severe circumstances, noble gases are generally very inert. Noble gases' inertness makes them ideal for situations where no reactions are desired. For example, argon is used in incandescent lights to keep the hot tungsten filament from oxidising, while helium is used in deep-sea divers' breathing gas to prevent toxicity from oxygen, nitrogen, and carbon dioxide (hypercapnia).