Question about Dispersion Formula

[Xuanyu_Ren_14A]

Since F₂ and Cl₂ are gases at standard room temperature while Br₂ is a liquid, this can be explained by the increasing polarizability due to larger electron clouds as you move down the group. However, according to the equation for Eq (α1α2/r^6), as electron cloud size increases, the distance between molecules also increases, which would typically reduce interaction strength. So why does the overall Eq value still increase?

[Purvi Vijayprakash 2C]

As you move down Group 17, the increasing size of electron clouds in halogens (like from (F2) to (Br2) makes them more polarizable, leading to stronger London dispersion forces. Although the distance between molecules slightly increases, the large boost in polarizability dominates, resulting in a net increase in intermolecular attraction. This explains why (Br2) is a liquid at room temperature, while (F2) and (Cl2) remain gases.