* Atomic Size: Bromine is located below Fluorine in the periodic table, meaning it has an extra electron shell. This makes bromine inherently larger than fluorine.
* Effective Nuclear Charge: While both elements have a greater positive charge in their ionic state (they gain an electron to become anions), the extra electron shell in bromine effectively shields the outer electrons from the nucleus. This weakens the attraction between the nucleus and the outer electrons, leading to a larger ionic radius.
In summary: As you move down a group in the periodic table, atomic and ionic radii increase due to the addition of electron shells and the decreasing effect of nuclear charge on the outermost electrons.
