Objects look and feel solid because of the strong electromagnetic force between the electrons in neighboring atoms. Even though atoms are mostly empty space, the electrons are confined to very small regions around the nucleus. When two electrons come close to each other, their wave functions overlap and they experience a repulsive force. This force is much stronger than the force of gravity, which is why atoms don't collapse under their own weight.

The combination of the repulsive force between electrons and the attractive force between electrons and the nucleus is what gives atoms their shape and structure. It also determines the physical properties of objects, such as their hardness, strength, and density.