I guess the important thing to realise is that the size atoms is irrelevant to the problem.
That doesn’t seem right, though? Imagine a one dimensional version of the problem. If a stick of length 1 is divided into n atoms weighing 1/n each, then each pair of adjacent atoms is distance 1/n apart, so the force between them is 1. Since there are n such pairs, the total force grows at least linearly with n. And it gets even worse if some atoms are disproportionately closer to others (in molecules).
That doesn’t seem right, though? Imagine a one dimensional version of the problem. If a stick of length 1 is divided into n atoms weighing 1/n each, then each pair of adjacent atoms is distance 1/n apart, so the force between them is 1. Since there are n such pairs, the total force grows at least linearly with n. And it gets even worse if some atoms are disproportionately closer to others (in molecules).