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. kimi7335

    I Distribution of satellite clusters around seed cluster in ATLAS

    From data of proton-proton collisions at the LHC using the ATLAS detector I have plotted a heatmap of the distribution of satellite clusters (brem and converted photons) around seed clusters (electron/photon candidates without satellites) at (eta, phi) = (0,0). The data I am using is of the...
  2. M

    B The Force of protons and quarks?

    How much force will it required to pull a quark out of a proton, and how much for to pull a proton out of a atom ?
  3. S

    I Probing into protons with high-energy particles

    What is easily seen about how the internal structure of proton is explored is collisions of proton with electrons of high and varied energy. Electrons have an advantage that they are simple particles easy to handle: muons and tauons are short lived neutrinos are hard to aim and detect other...
  4. S

    I Movement of protons between orbital bands in the nucleus

    What would happen if the protons started to have orbital movements with energy gain and loss, changing orbital bands, at the same time as the electrons?
  5. Sphere

    B What Happens to Very Energetic Protons After Collision?

    Hello, i was wondering, during the pair creation caused by the collision between a very energetic proton and a target (atomic nucleus) in a particle accelerator, what happens to the very energetic proton after the collision? Is it destroyed, intact, split into quarks or something else? Thank you!
  6. A

    B Can you create neutronium by colliding electrons and protons?

    Suppose in a Vacuum with no external influences we have two particle accelerators pointed at each other. They're maximally precise and one fires an electron while another fires a proton. Both the electron and proton have the same amount of momentum such that their x-axis velocity completely...
  7. J

    The acceleration of protons using a changing magnetic field

    If we increase the magnetic field, the radius of the particle's circular path will decrease which increases the tangential acceleration. How do I find the tangential acceleration. Do I use derivatives?
  8. F

    I A paradox for two moving protons?

    Before introducing Special Relativity, a textbook highlights the inconsistency of Maxwell's Electrodynamics and Newtonian Mechanics through the standard discussion about the velocity of light in different frames of reference. A further inconsistency discussed. In some inertial frame of...
  9. docnet

    B Entangled protons in a uniform magnetic field?

    In NMR, protons that are near each other exchange energy with each other by photon emission and absorption. Proton A is spin down, and proton B is spin up. proton A emits a photon and becomes spin up, and proton B absorbs this photon and becomes spin down. have the two protons been entangled?
  10. A

    Creating stationary neutrons by colliding protons and electrons

    Lets say, in zero gravity space, you have an incredibly precise collider that slams protons and electrons into each other as perfectly as possible such that all momentum is canceled out and the resulting neutron has no velocity relative to the observer. As protons and electrons continue to...
  11. Kostik

    I Why don’t two protons bind together?

    If the nuclear force is many times stronger than the electrical force, why don’t two protons form a stable helium-2 nucleus?
  12. Kostik

    A Distribution of protons inside a large nucleus

    For medium to large nuclei, common sense suggests that protons should not be uniformly distributed inside the nucleus. Assuming the protons inside the nucleus are mobile (but supposing that it doesn't make sense to consider the nucleus a "conductor", in which case all charge would reside on the...
  13. Adams2020

    I Loss of electron & proton energy due to radiation

    Can you compare the energy loss of electrons and protons due to the radiation they emit? In fact, I want to know which of the two loses more energy when it emits radiation.
  14. docnet

    How do I reconcile the biochemistry textbook descriptions of protons?

    One of the main lessons from general and organic chemistry was excess protons in aqueous solutions exist in the form of hydronium ions. However, in biochemistry textbooks, protons are individual in descriptions, for example, of the pumps in the electron transport chain, photosynthetic complexes...
  15. K

    Modelling an interation between two protons

    The image given with the problem: I found the original problem too difficult to solve, so I thought I'd make it easier by first considering the stationary proton as fixed in place. However, this too proved to be way more difficult than I expected. Here's the updated diagram I used in my attempt...
  16. A

    B Why are protons allowed in the nucleus?

    Feynman said in one of his lectures that electrons can't just fall down into the nucleus since the uncertainty principal wouldn't let them have a known position and momentum at the same time. The problem I have with this is that protons seem quite happy in the nucleus. Is my objection fair...
  17. B

    Heat distribution in a piece of glass receiving protons

    First of all, I didn't know whether to pick this subforum or the engineering/compsci one, I understand this might need to be moved to a more appropriate subforum. The general approach is fairly obvious, use implicit method to construct the tridiagonal matrix for Thomas method and solve. However...
  18. T

    In electrostatics, what is meant by positive charges?

    I am needing clarification for a concept. I understand that electrons carry a negative charge and that protons carry a positive charge. I also understand that a plastic rod picks up electrons when I rub it with a piece of wool. From the conservation of charge, the piece of wool must have a...
  19. Kharrid

    Kinetic Energy of Colliding Protons

    Summary: Finding the KE of a two proton collision that creates Kaons. Given the rest KE of protons and kaons, what is the minimum KE of one proton that can create the two kaons. In high-energy physics, new particles can be created by collisions of fast-moving projectile particles with...
  20. J

    B Can New Protons Be Created by Accelerating Particles to High Energies?

    Is it possible to create new protons, or is this ruled out by currently know physical laws?
  21. P

    B Are Protons Atoms? Is It True?

    Hello, my friend says a single proton would be considered an atom and I am saying it would not not. Technically protons are hydrogen ions, and my friend is referencing the definition of ions via WEBSTER -_- Webster says ions are atoms with an uneven number of protons to atoms. Therefore, by...
  22. L

    Find the concentration of protons

    After mixed, the volume is 200mL I am confused. The mol of H2SO4 is M*V 1M*100mL or 1M*200mL ? Finding the concentration of proton means the Molarity for H3O+ right? mol/volume H2SO4 + H2O -> H3O+ + HSO4- Mol H3O+ = Mol H2SO4?
  23. M

    I Does this hint of entanglement within protons suggest new physics?

    I'm happy to admit that I am struggling to digest this recent arXiv paper - https://arxiv.org/abs/1904.11974 - but I am interested in whether its reasoning and provisional conclusion seems insightful or merely interesting. My summary of their work is that the researchers consider colour...
  24. F

    Why do nuclei form in the first place if the protons repel each other?

    Now that I think about this some more, nucleons can get close together if they are traveling at a very high speed. So maybe when the Earth first formed, stuff was moving fast (or at high temperature/pressure) and this forced nucleons together into nuclei? I don't really know what I'm talking...
  25. K

    Magnetic field around a conductor with protons?

    Assuming that you can create a proton current. For example, the current of ionized hydrogen is analogous to a conductor. Question! Will a magnetic field be created around a conductor with a current of protons? By analogy with the magnetic field of electrons in a conductor.
  26. lilymay992

    What is the maximum speed of a proton if its kinetic energy is 1.28x10^-14 J?

    So first I tried to use KE=1/2 x m x v^2 but then realized I didn’t have the velocity and I can’t figure out a way to obtain it. I then tried to work out the energy using a different equation, W= q x v but that left me with 1.28x10^-14 J which seemed too small. I also then have to calculate the...
  27. MermaidWonders

    MHB Why Aren't Splitting Patterns & Integrations for Red & Blue Protons Different?

    For the colourfully-annotated compound above, why aren't the splitting patterns and integrations for the red and blue set of protons "pentet, 6 H" and "octet, 4 H", respectively?
  28. M

    Form Factor for Scattering (like muons off of protons)

    Homework Statement Homework Equations N/A The Attempt at a Solution I am trying to complete the last part of this question, part 5(c). My professor has told me that the form factor $$F(q)\rightarrow1$$ as $$q\rightarrow0$$ but I am unsure how to show this. I believe that $$\lim_{{q...
  29. Javier Lopez

    B Are electrons or protons attracted due to their magnetic moments?

    Does electrons or other particles attracted towards a magnet due its magnetic momentum?
  30. Javier Lopez

    B How Does Proton Spin Influence Its Magnetic Field?

    I do not understand the theory of moment of nuclei I read here: http://www.sjsu.edu/faculty/watkins/nuclearmoment3.htm that the magnetic moment of Hydrogen is 2.79284734 magnetons = 2.79284734*9.274009994e-24 joules/tesla =2.59e-23 joules/tesla So if I make to rotate a proton using 150 keV...
  31. G

    Magnetic Field from Protons vs Electrons

    If an electron is moving in a circle in a magnetic field, it produces a magnetic field in accordance to the right hand rule. If a proton is moving in a circle in a magnetic field, would it produce a magnetic field in accordance to the left hand equivalent to the right hand rule.
  32. N

    I Length Contraction of Protons in the LHC

    What affect does the phenomenon of "length contraction" have on the shape (e.g. spherical, rugby ball, barbell, donut) of protons accelerated to 0.999999991 c in the LHC?
  33. V

    I ZnS:Ag Detects 10 keV Protons in High Vacuum

    Hi I need to know if a thin mylar film with deposited ZnS:Ag is capable to detect low energy protons, say 10 keV, emitted in a high vacuum.
  34. Bikash Kumar Das

    B Meson particles emitted from neutrons and protons

    Neutron and proton are themselves not composed of mesons, then how do they emit these particles inside the nucleus?
  35. Hydrous Caperilla

    Location of electrons and protons

    Homework Statement a proton and an electron initially at rest ,combined to form a hydrogen atom in ground state.A single photon is emitted in this process.The wavelength of the emitted photon is Homework Equations E=hc/ λ The Attempt at a Solution e So I know when the system is formed the...
  36. A

    B How fast are the the protons in the large Hadron collider?

    Hi, I was asking how fast is the fastest Hadron ever moved in the large Hadron collider.And most importantly how do they calculate it? Do the calculate it mathematically or with a detector?
  37. I

    How to calculate protons and electrons in NH3BF3?

    Homework Statement As we know in NH3, N full fills its octet with three single bonds with H and a lone pair of electrons and so H. So this molecule is stable. In BF3, F full fills their octets by three single bonds with B but B is unable to fulfill its octet. It got 6 electrons by three single...
  38. S

    Problem about momentum uncertainty

    Homework Statement According to the Big Bang model of cosmology, the universe has been expanding since some initial time (call it t = 0) when the temperature was infinite. At early times, the temperature T scales as t^1/2 . The current temperature is about 3K. Consider the part of space which...
  39. D

    B Incurring hysteresis between protons in nuclei only....

    I'm curious if there is any documented effect along these lines, via EM waves. Hypothetically, all objects have a resonant frequency which will cause them to vibrate when matched. As an example, stone has a resonant frequency per type, its molecules also, atoms also, and I personally theorize...
  40. Const@ntine

    Chemistry Measuring the Mass & Electric Charge of Molecules

    Homework Statement Hi! So I stumbled upon this simple "plug n' play" exercise in my Physics textbook. Basically it gives you certain molecules/atoms, and tells you to measure the Electric Charge, and its Mass. Pretty simple, but I hit upon some hickups. Anyway, let's get to it: Find the...
  41. D

    What is the Speed and Number of Protons in a Van de Graaff Generator Beam?

    Homework Statement A Van de Graaff generator is one of the original particle accelerators and can be used to accelerate charged particles like protons or electrons. You may have seen it used to make human hair stand on end or produce large sparks. One application of the Van de Graaff generator...
  42. deuce123

    I Particle accelerator question -- when the protons "crash" particles are created

    I'm not sure if this is the right place for this question., but I'll ask anyways. So in particle accelerators when the protons "crash" particles are created because of the extremely high amount of energy(example of e=mc^2?)? Is that correct? Also, where do these particles come from? The Higgs...
  43. I

    I Differences in photons from protons vs photons from e-?

    In an effort to understand how an electron and proton attract each other in the QFT picture, I am wondering if there any differences at all between photons (virtual or whatever) emitted by electrons and photons emitted by protons? For instance, do photons from protons have a different spin or...
  44. I

    Speed of an object relative to another

    Homework Statement In a colliding beam apparatus, two beams of protons are aimed at each other. The first proton moves with a speed of 0.82c to the right; the second moves with a speed of 0.86c to the left. Both speeds are measured relative to the laboratory frame of reference. What is the...
  45. I

    Calculating Speed of Protons in a Linear Accelerator: 530 MeV Kinetic Energy

    Homework Statement In a proton linear accelerator, protons are accelerated to have a kinetic energy of 530 MeV. What is the speed of these protons? (The rest mass of a proton is 1.67 × 10-27 kg.) Homework Equations E0=m0c^2 E=E0/√1-(v^2)/(c^2) E = KE + E0 The Attempt at a Solution Recognize...
  46. J

    I T2 relaxation and Spin Echo of protons

    I’ve been reading on the physics of how a Magnetic Resonance Imaging (MRI) works from this link regarding the T1 and T2 relaxation time of protons. So far I understand the concept except what they’re trying to explain in the last 2 paragraphs about spin echo. This is what I got from these last...
  47. Eric Putney

    I Can a (uuu) baryon exist? If so, why wouldn't protons decay

    Is this some sort of issue with color or another quantity that needs to be conserved?
  48. David hzf

    Photons, Protons, and Electrons

    Photon is the force carrier for charged particles. Questions: 1. Are photons generated between proton and electron in an atom? 2. If yes who generate the photon? The proton or the electron? 3. If yes, quantum mechanically, the electron is never at a fixed position, what is the photon doing...
  49. S

    I Photoproduction of pions off protons

    A meson can be produced by a high energy photon scattering off a nucleon in an interaction such as $$\gamma + p \rightarrow p + \pi^0$$ As long as the photon is sufficiently energetic, mesons heavier than the pion can be produced, as well as multiple mesons such as ##\pi^{+} + \pi^{-}##...