How is one extra electron created? Are two electrons created by one neutron?
Here is how a beta decay proceeds:
note that the neutron turns into a proton, and electron and an electron antineutrino.
This increases the Z, i.e. the positive charge of the nucleus. The new atom becomes positive. If the energy of the electron produced is small, it will fill up the hole in the electron structure.Otherwise the atom will attract an electron from the ones in the fermi level, if it is a metal, or a positive hole will exist if it is an insulator.