Why is the size of (i) neon greater than fluorine ? (ii) sodium is greater than magnesium ?

(i) The size of Neon is greater than Fluorine because they are in the same period of the periodic table, but Neon is to the right of Fluorine. As we move from left to right in a period, the number of protons in the nucleus increases, which increases the positive charge of the nucleus and pulls the electrons closer to the nucleus. However, Neon has a complete octet, meaning it has a full outer shell of electrons. This full outer shell causes Neon to be larger than Fluorine because the electrons are more spread out.

(ii) Sodium is larger than Magnesium because they are in the same period of the periodic table, but Sodium is to the left of Magnesium. As we move from left to right in a period, the number of protons in the nucleus increases, which increases the positive charge of the nucleus and pulls the electrons closer to the nucleus. Therefore, the atomic radius decreases. So, Sodium has a larger atomic radius than Magnesium.