What happens to the size of atoms of elements of p-block as we move from left to right in the same period?

Size decreases

The correct answer is option 2. Size decreases.

As we move from left to right across a period in the p-block of the periodic table, the number of protons in the nucleus increases, leading to an increase in the effective nuclear charge experienced by the electrons. The effective nuclear charge is the net positive charge experienced by the outermost electrons, which is the actual nuclear charge (number of protons) minus the shielding effect caused by inner electrons.

Here is an explanation of why the size of atoms decreases as we move from left to right in the p-block:

Increasing Effective Nuclear Charge: As we move from left to right across a period, the number of protons in the nucleus increases by one with each subsequent element. This leads to a stronger attractive force between the positively charged nucleus and the negatively charged electrons. Although additional electrons are also added to the outer energy level as we move across the period, the increase in nuclear charge outweighs the increase in the number of electrons. This results in a higher effective nuclear charge experienced by the outermost electrons.

Effect on Electron Cloud: The increase in effective nuclear charge pulls the outermost electrons closer to the nucleus. Since electrons repel each other due to their negative charges, the outermost electron cloud contracts as the electrons are pulled closer to the nucleus. Consequently, the atomic radius decreases as we move from left to right across the period. The atomic radius is defined as the distance from the nucleus to the outermost electron cloud, and this distance decreases as the electron cloud contracts.

Trends in Atomic Size: The decrease in atomic size across a period is consistent for elements in the p-block of the periodic table. This trend is observed from left to right in each period, reflecting the increase in nuclear charge and the corresponding contraction of the electron cloud.

In summary, the size of atoms in the p-block decreases as we move from left to right across a period due to the increasing effective nuclear charge, which pulls the outermost electrons closer to the nucleus, resulting in a contraction of the electron cloud and a decrease in atomic radius.