A very strong short range attraction
The cohesion of the nuclear structure is mainly due to the attractive strong force, which is capable of overcoming the electrical repulsion the protons exert on each other. This ‘strong force’ is only effective over short distances, as a nucleon passing very close to a nucleus will not feel its influence. The force only starts to apply when direct contact is made – to symbolise this ‘nuclear glue’, the nucleons and nuclei above have been drawn with a layer of glue surrounding them.