can electrons and protons combine to make a neutron?

Question

i've heard that this happens in neutron stars, but it seems to defy logic, can it really happen, and if so, how? also, if there is matter that is made almost entirely of neutrons, then can there be matter made of only protons, or only electrons?

Answer 1

Electrons, protons, and neutrons are made up of smaller particles called quarks. Different types of quarks in different combinations go together to form speicifc particles. For some interesting info about what quarks are and how they go together to form the sub-atomic particles, visit the following site which will start you on the proton but has a link for the neutron and go from there. Enjoy.
you cannot have an object made up of only protons or electrons. Similar charges repel. Protons all have a positive charge, electrons are all negative charged, they would repel each other. There must be something to overcome the electromagnetic force repelling them. This only happens when neutrons are present since neutrons are controlled by the strong nuclear force. Before I start going on and on, just visit the website. :)

Answer 2

During a supernova, the electrons & protons are crushed together to make neutrons. In fact, *many* of the neutrons around us today are the result of such a combination when particles formed after the big bang's fireball cooled enough.

The reason neutron stars are so dense is that there is no space between all it's components. All matter around us is virtually composed of empty space - with material made of nothing but neutrons, there's no repulsion between particles, so they condense right next to each other.

You can't really have 'matter' made up of only protons, or electrons, although there are free individuals roaming around space right now. Even if two or more protons were to overcome their electrostatic repulsion of each other, without an orbiting electron, it's basically just a one or two or three proton nucleus - and very small, when compared to 'normal' atoms.

Answer 3

The reaction where a proton and an electron fuse to form a neutron is essentially the reverse reaction of beta decay. In this, an electron neutrino will be emitted. This reaction is mediated by the weak nuclear force.

Matter made out of just protons or just electrons would be unstable because of the electric force, which would blow such matter apart. Neutrons are electrically neutral, so the strong force is the dominant force.

Answer 4

Yes, it is possible. We know that free neutrons spontaneously decay into hydrogen atoms, liberating energy. Since all neuclear reactions are reversible, it is possible, but the reaction is endothermic, meaning you must add in some energy in order to make it happen. Actually, our sun is converting electrons and protons into neutrons all the time, to the tune of trillions of tons per second, in the form of proton-proton nuclear fusion. Two protons get close enough for the nuclear strong force to take over and allow them to fall together and fuse into one nucleus. This double proton nucleus is highly unstable and then immediatly emits a positron and a gamma ray, and maybe a neutrino, with the end result being a Deuterium nucleus, which is a proton and a neutron stuck together. This then goes on to form Helium-3 and then two of these combine to form Helium-4 and two protons. The net effect is to take four protons and make one alpha particle, which is two protons and two neutrons.
There is another nuclear reaction that occurs with very heavy elements called "K-capture" in which a large nucleus reaches out and captures an electron, converting one of its protons into a neutron. I hope this helps.

Answer 5

It cannot happen except in the densest, highest-gravity environments.

As for whether there can be only-proton or only-electron matter: no. Neutrons are electrically neutral (hence the name), and therefore do not repel one another. You cannot ever have two protons in close proximity to one another without something else to balance out the repulsive force.

Additionally, even one proton in space doesn't stay lonely for long. Because it has a positive charge, it attracts negative charges (and vice-versa for electrons).

Answer 6

yes they can, but it needs to be very dense to get the close enough. and i havent heard of an object being made entirely of protons, i think it is because they have a stronger magnetic feild than neutrons, and they are more massive than an electron, but there are stars made of electrons called white dwarfs. their the result of a star not big enough to create a neutron star.