I was watching an explanation (found here) on nuclear fission. In the video, she described the process of fission to happen one a random neutron smashes into a uranium nucleus. This causes the nucleus to split into krpyton and barium, taking part of the nucleon and electrons with it, along with a few extra neutrons. The extra neutrons then smash into other uranium nucleuses, causing the chain reaction.
My question is, if you start with only $x$ electrons in the original uranium atom, you must run out of electrons soon in the chain reaction. Where do the extra electrons, needed to continue the chain reaction, come from?