According to Internet, a big mess… (I asked Copilot…)

If atoms were to double in size, it would have profound consequences on the physical world as we know it. The size of an atom is determined by the space its electrons occupy around the nucleus. Doubling the size of atoms would mean that the electrons are further away from the nucleus, which would weaken the electromagnetic forces that hold atoms together.**

Here are some potential effects:

Chemical Bonding: The formation of chemical bonds could be significantly affected. Atoms might not be able to form multiple bonds, such as double or triple bonds, because the overlap of p orbitals would be less likely as they get farther apart.

Material Properties: The properties of materials would change drastically. For instance, metals might lose their conductivity because the delocalized electrons that allow for the flow of electricity would be too spread out. Biological Structures: The structures of proteins and DNA would be altered, potentially disrupting all biological processes. Enzymes might not function properly, and the basic mechanisms of life could fail. Physical Laws: The fundamental constants and laws that govern physical interactions would need to be redefined to accommodate the new atomic sizes. It’s important to note that this is a hypothetical scenario and not currently possible according to our understanding of physics. The size of atoms is a fundamental aspect of quantum mechanics and chemistry, and any change in atomic size would mean a change in the fundamental laws of nature.