The picture shows a close-up of one carbon atom. A hydrogen atom has one proton as the nucleus and one electron in the region outside the nucleus. The electron and proton are attracted to each other.

Protons are a key ingredient of every atom, the simplest of which is hydrogen (one proton and one electron.) But storing protons as loose particles and then moving them onto a truck is a challenge ...

When two hydrogen atoms get close enough, the electron from each atom feels an attraction from the proton in the other atom's nucleus. This attraction pulls the atoms together. The electrons end up ...