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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?

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    $\begingroup$ The electrons don't really play a part in the (neutron+Uranium) fission reaction and the total number of electrons remains unchanged. Are you sure you didn't mean to ask something else? $\endgroup$ – Squid Jan 8 '17 at 4:48
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A possible fission reaction equation is as follows:

$$^{235}_ {\;92}\rm U +_0^1n\rightarrow ^{236}_ {\;92}U\rightarrow ^{140}_ {\;54}Xe+ ^{94}_ {38}Sr+2_0^1n$$

This equation is balanced if neutral atoms are produced.
Even if ions were produced there would still balance of positive and negative charges.

$\rm ^{140}_ {\;54}Xe$ and $\rm ^{94}_ {38}Sr$ are radioactive because they are neutron rich and undergo beta decays which converts neutrons into protons in the nucleus with the emission of fast moving electrons (beta particles).

$\rm ^{140}_ {\;54}Xe$ undergoes four beta decays and ends up as $\rm ^{140}_ {\;58}Ce^{4+}$ and four electrons have been emitted.
Eventually the $\rm ^{140}_ {\;54}Xe^{4+}$ finds four electrons (or the intermediate products collect electrons) and a neutral atom is produced.
Similarly the $\rm ^{94}_ {38}Sr$ undergoes two beta decays, collects two electrons and forms an atom of $\rm ^{94}_ {40}Zr$

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The electrons balance the number of protons in matter, and the total charge is zero, and there is the law of conservation of charge.

Protons and electrons do not decay . There can be no running out of electrons (or protons) except temporarily , until the new nuclei gather by electromagnetic attraction the necessary electrons for the new nuclei to become neutral.

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