It's a problem of nuclear physics - the stability of a nucleus, depending on the number of protons and neutrons.
a free neutron can trigger the split of a particle like uranium 238. It will produce a smaller atom (eg. proctantium), a beta particle and energy.
uranium
The answer is neutron. :)
Yes, by nuclear fission.
Neutrons
Neutrons
They split the uranium atom.
The atom of uranium can split in a process called nuclear fission to generate electricity in nuclear power plants.
The nuclear fission of uranium is a reaction with neutrons.
Nuclear fission
Probably you think at fission products.
Each atom, when split, releases one or more neutrons. Those neutrons go on to destabilize and split other atoms. This is the "chain reaction" we talk about. The multiplication factor, known as Keffective represents the rate of increase in reactivity. If Keffective is 1, then, on average, one atom's split results in one neutron that splits one atom.