How can materials be waterproof or air tight if atoms don’t touch?

Question

How can materials be waterproof or air tight if atoms don’t touch?

In: Physics

Answer 1

Actually, the short answer is that they can’t. Some incredibly tiny amount of air or water will consistently leak in.

However, even if the molecules don’t touch, they are held together by electrostatic forces. Forces which prevent them from getting any closer together. These forces also prevent *other* molecules from getting closer to them. Water molecules, for instance.