What would happen if an electron collided with a proton such that the two do not collapse? Would the two become a unit, or would some force prevent them from bonding thus forcing the electron to orbit around the proton?


I'm not sure what you mean by "collapse", but if I interpret that as "no hydrogen is formed" or "the electron is not captured", then 2 things can happen:

1) Elastic electron-proton scattering: the electron and proton just "bounce" off each other under some angle theta. By observing the cross section of the scattering versus the theta angle it was shown that proton is not a point particle, but an extended object.

2) Deep inelastic scattering: the incoming high energy electron "destroys" the proton into a bunch of outgoing hadrons (mostly pions). By observing the cross section of this interaction it can be shown that proton is composed of pointlike particles. The electrons collide elastically with a parton.

Some details are here.

  • $\begingroup$ By collapsing I mean that which you have mentioned in your second statement...if the two particles were to be involved in an inelastic collision,would they become a unit and travel together as a joint,as the columb's force will be holding them together,or would some force prevent the electron from getting much closer... $\endgroup$ – user34793 Nov 27 '13 at 9:09
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    $\begingroup$ Electron and proton never stay "glued" to each other. They can scatter (products of the collision flying away), or they form a hydrogen atom. Alternatively the electron can be captured, but after a capture the electron and proton do not exist enymore: there is a neutron and a neutrino. $\endgroup$ – mpv Nov 27 '13 at 9:23
  • $\begingroup$ In a hydrogen atom the electron is attracted to the proton by electromagnetic interaction (Coulomb "force"). But the electron cannot get too close - it just stays in an orbital. The reasons behind that are quantum mechanical. One simplified (but not perfect) explanation says that squeezing the electron too close to the proton makes the electron exist in very small space and thus via the Heisenberg uncertainty its momentum can be very high. This "pushes" the electron farther away from the proton. $\endgroup$ – mpv Nov 27 '13 at 9:27
  • $\begingroup$ When you said: the incoming high energy electron "destroys" the proton into a bunch of outgoing hadrons (mostly pions) did you mean mesons because pions are mesons? $\endgroup$ – Chess_Player 21 Jan 30 '17 at 17:36

depends on the energy of the electron. For low energies, a bound state will be formed due to electromagnetic interaction between the two. In the case of higher energy, the proton can be transformed into a neutron.


The collision between these two can produce a neutron emitting neutrino and atom may be unable of bonding and molecules will never get formed. Then new and different chemistry will take birth.

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    $\begingroup$ Welcome to Physics.SE! This answer is not particularly clear. Consider expanding on it, adding information, clarifying your statements, and explaining the reasoning behind it. $\endgroup$ – Jim Aug 20 '14 at 17:25

a hydrogen atom is an electron orbiting a proton, not the product of their collision. a high energy collision would produce a neutrino and a neutron.

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    $\begingroup$ $e + p \to n + \nu_e$ is a very rare outcome for a high energy collision. For instance $e + p \to e + p + \pi^0$ or $e + p \to e + \Delta^{++} + \pi^-$ are both far more common. $\endgroup$ – dmckee Jan 19 '15 at 16:35

protected by ACuriousMind Nov 7 '16 at 16:30

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