What is Protons: Definition and 341 Discussions

A proton is a subatomic particle, symbol p or p+, with a positive electric charge of +1e elementary charge and a mass slightly less than that of a neutron. Protons and neutrons, each with masses of approximately one atomic mass unit, are jointly referred to as "nucleons" (particles present in atomic nuclei).
One or more protons are present in the nucleus of every atom; they are a necessary part of the nucleus. The number of protons in the nucleus is the defining property of an element, and is referred to as the atomic number (represented by the symbol Z). Since each element has a unique number of protons, each element has its own unique atomic number.
The word proton is Greek for "first", and this name was given to the hydrogen nucleus by Ernest Rutherford in 1920. In previous years, Rutherford had discovered that the hydrogen nucleus (known to be the lightest nucleus) could be extracted from the nuclei of nitrogen by atomic collisions. Protons were therefore a candidate to be a fundamental particle, and hence a building block of nitrogen and all other heavier atomic nuclei.
Although protons were originally considered fundamental or elementary particles, in the modern Standard Model of particle physics, protons are classified as hadrons, like neutrons, the other nucleon. Protons are composite particles composed of three valence quarks: two up quarks of charge +2/3e and one down quark of charge −1/3e. The rest masses of quarks contribute only about 1% of a proton's mass. The remainder of a proton's mass is due to quantum chromodynamics binding energy, which includes the kinetic energy of the quarks and the energy of the gluon fields that bind the quarks together. Because protons are not fundamental particles, they possess a measurable size; the root mean square charge radius of a proton is about 0.84–0.87 fm (or 0.84×10−15 to 0.87×10−15 m). In 2019, two different studies, using different techniques, have found the radius of the proton to be 0.833 fm, with an uncertainty of ±0.010 fm.Free protons occur occasionally on Earth: thunderstorms can produce protons with energies of up to several tens of MeV. At sufficiently low temperatures and kinetic energies, free protons will bind to electrons. However, the character of such bound protons does not change, and they remain protons. A fast proton moving through matter will slow by interactions with electrons and nuclei, until it is captured by the electron cloud of an atom. The result is a protonated atom, which is a chemical compound of hydrogen. In vacuum, when free electrons are present, a sufficiently slow proton may pick up a single free electron, becoming a neutral hydrogen atom, which is chemically a free radical. Such "free hydrogen atoms" tend to react chemically with many other types of atoms at sufficiently low energies. When free hydrogen atoms react with each other, they form neutral hydrogen molecules (H2), which are the most common molecular component of molecular clouds in interstellar space.
Free protons are routinely used for accelerators for proton therapy or various particle physics experiments, with the most powerful example being the Large Hadron Collider.

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  1. D

    How electrons and protons and atoms make a whole object

    heisenbergs uncertainity says that we can never predict the position and velocity of a particle exactly simultaneously. that is we can never be sure where an electron or a proton would be seconds from now. its all about probablity. then how can these particles together form something like we...
  2. Iron_Man_123

    Which of the following is not an example of ionizing radiati

    Homework Statement Homework Equations Between Radio Waves and Protons is where my confusion lies; Online I read that Radio waves are non ionizing but if that's the answer then how are protons ionizing? I mean it's no even included in the types of ionizing radiation here...
  3. DarkBabylon

    B High energy protons and electrons to gamma radiation

    Can high energy incoming protons and electrons be absorbed and their energies remitted by photons? If so what are the typical ranges of energies emitted and are they heading in the same direction as the original emission if we had a sheet of metal being bombarded by those protons and electrons?
  4. LarryS

    I How are protons, photons and quarks related electrically?

    When protons, due to their electric charge, interact with photons are the quarks somehow also involved in this same electric interaction? After all, the quarks do have fractional electric charges. Thanks in advance.
  5. gennarakis

    I Quantum Kinetic Energy of Neutrons, Protons and Electrons

    Hi there, I have a problem to solve in Cosmology which says: "Write the formulas for the quantum kinetic energy of neutrons, protons and electrons as well as the formula for the gravitational energy for a neutron star that is comprised of free neutrons, protons and electrons in a ratio of Nn ...
  6. Behrouz

    Exploring the Nature of Charge in Electrons and Protons

    Is it right to say that 'modern physics has no deep explanation of the nature of charge' in electrons and protons?
  7. Zoey

    Does an Atom's Type dictate the Protons and Neutrons?

    Hi, Does an Atom's Type have to do with the number of protons and neutrons it has? Or are they completely unrelated? Just curious. Thanks :)
  8. P

    Electric Field Homework: Rank Protons by Acceleration

    Homework Statement The figure below shows five protons that are launched in a uniform electric field E (green). The magnitude and direction of the launch velocities are indicated. Rank the protons according to the magnitude of their accelerations due to the field, greatest first. Justify...
  9. Titan97

    Three protons and two positrons....

    Homework Statement There protons are and two positrons are held such that two protons are on the ends of a diagonal of a square and the two positrons are on the ends of the second diagonal. The third proton is situated at the centre of the square. The system is released from rest. Find the...
  10. P

    How close can two protons get if....

    Mentor note: Thread got moved to the homework section How close can two protons get if one is at rest and the other has a kinetic energy equal to the average energy at T =107 K? I know that the kinetic energy of the moving proton is 3/2kT, but what is the kinetic energy of the proton at rest...
  11. J

    Electrostatic analysis of cad model of protons neutrons

    Could the orbit filling order of electrons be more classical and less quantum? I attached a jpeg and need someone to do a electrostatics analysis of the CAD model version of it. Does anyone have an electrostatics software package and have time to do a finite element analysis on a 3-D part to...
  12. Mr Tompkins

    Wikipedia.org -- Protons captured by neutral gas atoms?

    A quote from wikipedia: "At sufficiently low temperatures, free protons will bind to electrons. However, the character of such bound protons does not change, and they remain protons. A fast proton moving through matter will slow by interactions with electrons and nuclei, until it is captured by...
  13. S

    How to simulate protons on a computer program to observe them?

    Well I'm in grade 11 and for an investigation I decided I'd observe the behavior of protons once the neutrons and electrons are removed from the atom. Specifically I want to observe how the acceleration at which the protons move apart from each other varies with the mass of the atom (i.e. #...
  14. O

    What is an elementary particle?

    When my eighth grade daughter was studying physics in her class, I watched a movie with her on the Hadron Collider (" Particle Fever "). We discussed atoms, electrons, protons, neutrons; we discussed orbits and statistics, and then down into the standard model and fermions, leptons, yadda...
  15. N

    Electrical Fields within the body

    So I was thinking, if the body has its own electrical currents... especially in the brain, then the brain must have an electrical field that extends infinitely. If that is the case can the brains electrical field interact with the real world and influence it. So for example if the field was...
  16. 1

    How does protons has mass and not pions?

    hi, I've heard that protons has most of their mass from their electromagnetic and strong interactions between their quarks, but specifically, how does that make mass? and if so, what is intrinsic mass then? and pions has 2 quarks and strong and electro interactions, why doesn't it has mass...
  17. Buzz Bloom

    Question re equilibrium abundance of a protons and electrons

    I am thinking of a time period between two events: 1. After the annihilation of most protons/neutrons with all anti-protons/anti-neutrons, and 2. Before the annihilation of electrons and positrons. During this period the temperature decreases from T1 to T2. T1 is the highest temperature at...
  18. E

    Question regarding decay, protons and neutrons

    Homework Statement [/B] You find a 1kg piece of rock containing 3 elements: Fakium with 50 protons and 52 neutrons imaginium with 52 protons and 48 neutrons madeupium with 51 protons and 51 neutrons Fakium is known to be radio active, Which of the other two elements could be the decay product...
  19. S

    Distribution of protons in momentum space in an ion source?

    How are protons in an ion source distributed in momentum space? Consider an ion source fed with H2 at low pressure. As soon as the protons are free protons they are accelerated by the extraction voltage of perhaps 10 kV. In momentum space the protons are initially a "shell" with a certain...
  20. Eli137

    Is the tetraneutron a real element without any protons?

    I have heard of the tetraneutron, but is it real? Could it have electrons? If so, how unstable would it be? Could fermions not typically in an atom balance this instability?
  21. S

    I Would protons in LHC lose energy over time if ejected out?

    I googled this and didn't find anything. But it's a simple question. If a proton was moving 99.999% the speed of light in the LHC, and the Earth and LHC and everything around it disappeared, would the proton lose speed or energy overtime? assuming no background radiation etc. A simpler way of...
  22. C

    Do protons have stong nuclear interaction with other protons

    I was wondering if protons exchange strong nuclear interaction/force with other protons or do protons exchange strong nuclear interaction/force with just neutrons OR do all protons and neutrons exchange strong nuclear interaction/force with all protons and neutrons. Protons exchanging strong...
  23. Devin

    What is the frequency of proton oscillation?

    How do protons oscillate? Do they move back and forth with a constant velocity, or sort of like a mass on a spring? If so, what is the frequency of oscillation? Thanks
  24. godzenon

    Protons and electromagnetic attraction in the LHC?

    Thanks for reading this As protons go faster and fast in the LHC they have a greater angular momentum (that's not at all the right term) to go around in circles faster and faster as they reach near the speed of light that greater inward attraction towards the magnet to rotate around in the LHC...
  25. Ryan Reed

    Do Protons and Neutrons Move around in the Nucleus?

    Protons and Neutrons vibrate in place, but do they change positions within the nucleus? Let's say that there's a helium atom which has two protons and two neutrons. If the particles were set up on the corners of a square for easy representation with a neutron on the top left and top right, and a...
  26. H

    Do sound waves affect the distance between protons in an atom?

    When an atom vibrates more than usual, say for example effected by a sound wave, do it's protons repel each other further apart than normal? Thus more charged virtual Pions occurring and decaying (discombobulating) into virtual W+ bosons? Edit: I know that accelerated charged particles create a...
  27. M

    Speed difference between protons & heavy-ions in LHC?

    On the wiki-pages it says that in the LHC protons travel 3m/s slower than c. I was curious what it would be for heavy-ions; is it maybe 15m/s because their energy is ~5 x lower (7 vs. 2.76 Tev) ? And a small question on the side, does Gravitation assistance have a bigger impact on speeding up...
  28. james gander

    How do we know quarks aren't just parts of broken-up protons

    Please be esy on me for asking what seems a very silly question but i have only just started reading about this sort of thing very recently. I can only learn by asking so please bear with me. thanks My question is, how do we know when we have found a new particle, for example when physicists...
  29. mfb

    Insights LHC Part 3: Protons as Large as a Barn - Comments

    mfb submitted a new PF Insights post LHC Part 3: Protons as Large as a Barn Continue reading the Original PF Insights Post.
  30. T

    Accelerating protons and antiprotons for pair production?

    Okay so I have a problem with what my textbook is saying. It defined pair production as a process in which a photon of electromagnetic energy is converted to a pair of particles. But then it gave the discovery of an antiproton. Which was when a proton was accelerated to 6MeV and collided into...
  31. AndrewC1994

    Protons along a magnetic field line

    1. A Magnetic field line has a length of 70,000 [Km], for this example all particles have an energy of 1.6E-27 [J]. Assuming all motion is parallel to the magnetic field line how long would it take to complete this cycle.2. M[Proton] = 1.677E-27 [Kg] , M[Electron] = 9.1E-31 [Kg] , E[kinetic] =...
  32. binbagsss

    Gauss's law, nucleus, potential proton due to other protons

    I'm a little out of touch with this stuff , but I'm really not getting it.. So my book is considering: in a nucleus of ##z## protons, consider one proton in spherical charge distribution to other protons. So ## \rho = (z-1)e/(4/3) \pi R^{3}##, where ##R## is the radius of the nucleus, is the...
  33. R

    Is it possible to deduce the number of protons from the mass

    ...number? If you are give say Lead, 208Pb. What is the 208? and is it possible to deduce the number of protons Z from it with no other information? Haven't done chemistry yearts so any help would be appreciated.
  34. H

    EM wave from electrons V protons

    this is theoretical (and possibly stupid) question; accelerating protons would create an EM wave equivalent to an EM wave generated by electrons at same frequency but the amplitude would be opposite, is that possible. has anyone made a communication circuit from accelerating protons? are...
  35. Q

    Inside protons: origin of the sea quarks

    I have seen in many places, for example here, the statement that the proton consists of valence quarks and sea quarks. I am somewhat confused as to where this picture comes from. The sea quarks are virtual quark-antiquark pairs. I have encountered virtual particles only in the context of...
  36. D

    Is current the flow of protons or just the movement of holes

    I know that current flows in the opposite direction of electrons but I'm confused as to whether it is the movement of holes like in a semiconductor or if there are actual positive particles flowing that way.
  37. R

    NMR: Why do "identical" protons not experience splitting?

    Hey, I've been trying to figure out why a protons in identical environments will not undergo spin-spin splitting with one another. From what I understand splitting of a signal for a proton is due to the nucleus of another nearby either opposing the external magnetic field or acting in the same...
  38. N

    Difference between Delta particles and protons and neutrons

    I am trying to figure out the difference between Δ0 and Δ- and the proton and neutron since both appear to have the same combinations of up/down quarks. Deltas have isospin 3/2 and spin angular momentum 3/2 whereas protons and neutrons have isospin 1/2 and spin angular momentum 1/2. I'm...
  39. O

    What happens when a proton and an electron collide?

    I know this question sounds... find a word for it you like... But please bear with me. A proton. An electron. Not very high speeds...Vacuum.. A proton has an electric field, so does an electron... They arrive into each others' fields and start to accelerate towards each other... What...
  40. H

    Electrons & Protons: Why Revolve Around Nucleus?

    why do electrons revolve around the nucleus?
  41. A

    Isolation of protons and alpha particle

    Hi, I wanted to ionize hydrogen and helium to get protons and alpha particles. I then want to smash the protons into the alpha particles. Is it better to accelerate both the alpha particle and the proton or just keep the alpha particle as a target for the proton to hit? Or is there a better way...
  42. N

    What is the cause of an atom's number of protons

    Why is it that one atom such as hydrogen has one proton while others have many. What is the mechanism driving this force which causes some atoms to be marked for one protons and others for many? And once they are say marked as hydrogen they can be nothing else, correct? Since hydrogen is the...
  43. M

    Should we describe protons and electrons in dar Matter in a different way?

    I was wondering if protons and electrons have different description in the terms of quarks if they're in Dark Matter??
  44. gauss44

    Van Allen Belt: Why are electrons generally further out?

    Why are electrons generally further out than protons in the Van Allen Belt?
  45. S

    Graphene Allows Protons to Pass Through

    Andre Geim & Co have discovered that graphene can act as a sieve which allows protons to pass through it, while blocking other atoms and molecules: http://www.independent.co.uk/news/science/scientists-predict-green-energy-revolution-after-incredible-new-graphene-discoveries-9885425.html...
  46. A

    Fraction of protons scattering

    Homework Statement A proton beam of energy E=7mpc2 is incident on a cylindrical volume (V=20 cm3) of liquid hydrogen (density ρ=0.071 g cm-3) at rest. The spot area of the beam is A=4 cm2 and the total cross section is σ=30 mb. What fraction of the protons entering the target will interact...
  47. ryanuser

    Can we stop protons from moving in LHC?

    Hi my question is simple, can we make the protons stay in a fixed position (not accelerating them) in LHC by using the powerful magnets there? Thanks
  48. O

    Number of protons and electrons

    How can I find the number of protons and neutrons of any element without looking the periodic table. And I need them each so mass spectrometer won't work Edit: I noticed that my title is wrong, explanation of the number of electrons are not needed
  49. N

    Repulsive force between 2 protons?

    Homework Statement I have 2 protons 1 femtometer away from each other, what is the repulsive force between them? q1 = 1.6x10-19C q2 = 1.6x10-19C r = 1x10-15m K = 9x109Nm2/C2 Homework Equations FE=Kqqqw/rw The Attempt at a Solution My answer comes out to be -230.4N but I...
  50. J

    What is the work required to push three protons to form an nucleus?

    Hello there, Imagine that a nucleus consists of three atoms arranged in a equilateral triangle with the length of each side, ##R=2 \rm fm##. Our protons starts infinitely far away. What is the work required to push these protons together in order to overcome the electric force between them? I...
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