Neon (Ne) has a larger atomic size compared to the magnesium ion (Mg+2).
The atomic size, or atomic radius, refers to the distance between the nucleus of an atom and its outermost electron shell. In general, as you move across a period (horizontal row) of the periodic table from left to right, the atomic size tends to decrease due to an increase in effective nuclear charge, which attracts the electrons more strongly and pulls them closer to the nucleus.
Mg+2 is a positively charged ion that has lost two electrons from its neutral magnesium atom. When an atom loses electrons to form a cation, the effective nuclear charge becomes greater because there are fewer electrons to shield the positive charge of the nucleus. As a result, the remaining electrons are pulled closer to the nucleus, leading to a decrease in the atomic size of the ion compared to the neutral atom.
On the other hand, neon (Ne) is an element located in the far right group of the periodic table, specifically in the noble gases. Noble gases have completely filled electron shells, making them very stable. The stable electron configuration of neon results in a larger atomic size compared to magnesium ion (Mg+2) because the electrons in the outermost shell are further away from the nucleus and are not strongly attracted.
Therefore, Ne has a larger atomic size than Mg+2 due to its electron configuration and position in the periodic table.