There are no positive or negative charges. The nucleus absorbs photons that are emitted by the electron. Tus the outward pressure pushes the electron towards the nucleus/ or in other words the energy level changes such way that the radius gets smaller. We have been lied hundreds of years. The theory of perfect negatives and positives sounded too childish to be true anyway.
https://physics.stackexchange.com/questions/57874/do-protons-exchange-photons-with-electrons