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.
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...
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...
hi,
im new to the whole subject of particle physics. I've searched for a long time and couldn't find an answer to a very simple question. WHY PROTONS?? why did they spend 8 billion dollars to build a collider to collide protons? why not electrons for example? why do they think that colliding...
I wondered if anyone could help me with a question. Do acids such as HCl donate protons because the conjugate acid is more electronegative? Such as the O in H2O is more EN than Cl, and that's why the H+ dissociates?
I am wondering how Muons are manufactured.
Wikipedia says they're the decay products of cosmic rays, and that cosmic rays are usually high energy protons.
So a high energy proton (cosmic ray) decays into a muon after colliding with matter on earth.
How is consistent with the fact that...
Friends,
I came across an old (2010) "U" Tube video. It said that recent studies indicated that Protons may actually be about 4% smaller than previously thought.
https://www.youtube.com/watch?v=OnnnJlXvwN8&list=UUvBqzzvUBLCs8Y7Axb-jZew
{Anyone know whether this has been corroborated or...
Homework Statement
Why are protons in the nucleus and electrons aren't??
The Attempt at a Solution
So this is the question I was asked. I understand that protons are held together by nuclear (or strong) force. I understand that an atom is stable because there's an equilibrium...
I am looking at the structure of protons, and in my script, when they define the Parton Distribution Functions of all parton species they say that the integral over PDFs of all parton species yields a total momentum fraction of:
\sum_i \int_{0}^{1} f_{i}(x) x dx =1
where i denots the...
to the untrained eye electrons and protons seemed to be very different, different size, mass and composition but they have the same quantity of charge (ignoring the sign). why is this?
An even more fundamental question: what is it about an electron or proton which gives it its charge in the...
dear sir,
i heard that that proton spins about itselfand this helps in stability of nucleus. i also heard from the a friend that neutron has a proton and electron within it. this electron moves out from neuton making it proton and entering proton to form a neutron. sir i need to know...
Homework Statement
What is the minimum proton energy needed in an accelerator to produce antiprotons by the
reaction:
P+P \rightarrow P+P+P+\bar{P}
The mass of both protons and antiprotons is m_p. Assume first that the initial protons have equal
energy (the lab frame is the...
Inside of circular region of radius 10cm shown in Figure 5(a) there is
a uniform magnetic field pointing upwards and three protons held in
place: one at the center, one at a distance of 5cm from the center and
one at a distance 15cm from the center e there is no magnetic field.
The...
Hi All,
I am preparing for PhD quals and have been looking at problems from other universities. I came across this one and am stumped on how to tackle it.
" Assume that the neutron density in a neutron star is 30.1/fm (that is 0.1 neutron per
cubic Fermi). Assuming T=0 and ignoring any...
Homework Statement
Hi , in the first chapters of my physics book states that positive charges don't move , but now this new chapter about curruent and resistance says that the direction of the current is the direction in which the positive charges flow or move . I'm confused :confused:
Can...
I find it confusing, I tried to google the topic but I still don't get it. What is the size and shape of subatomic particles? do they have a size or shape at all? and does the fact that protons and neutrons have larger mass than electrons mean they're bigger in size?
Hello,
Ive been seeing it everywhere" NAOH is a strong base".
But in order for it to be strong, it has to meet the requirements which are:
-The Kb of the reaction 6qvtA.pngmust be high. This means that base strenght is not determined by the dissociation % of a substance.
Now I ve seen a...
X-ray crystallography is now 100 years old so this question is probably pretty simple. Is the diffraction coming from the nucleons or the electrons in the sample? Ie. The electrons occupy a more diverse location within the sample (depending on what level/shell they occupy, in fact some may be...
Is the most stable/likely configuration of protons in heavy nuclei that of being evenly distributed throughout the nucleus? As opposed to something like a spherical distribution?
Homework Statement
Two protons are released from rest, one from location 1 and another from location 2. When these two protons reach location 3, the first proton has a speed that is 4 times the speed of the second proton. If the electric potentials at locations 1 and 2 are 231 V and 115 V...
Do protons and neutrons have excited states?
This page shows some simulated shapes of protons. http://discovermagazine.com/2003/aug/breakprotons
Do the different shapes have to do with different energy states of the proton?
I've just recently learned that protons do in fact have a charge, I was wondering if someone could explain this, as far as applying a positive charge, some real world examples. I've always studied current as a flow of electrons, never heard of a flow of protons before and have no idea what it...
H2SO4 + H2O -> HSO4- + H3O+
A question by a noob.
I get the fact that water can act as an acid and as a base. The oxygen "pulls" the hydrogen+ ion away from the sulfuric acid oxygen hydrogen bond an gets one itself and becomes positively charged, therefore a hydronium.
However, I wonder...
Homework Statement
Consider the electric field of two protons b meters apart.
The potential energy of the system is equal to:
U = \frac{\epsilon_0}{2}\int {\bf E}^2dv = \int({\bf E}_1+ {\bf E}_2)^2dv
= \frac{\epsilon_0}{2}\int {\bf E}_1^2dv + \frac{\epsilon_0}{2}\int {\bf E}_2^2dv +...
Hi,
suppose we have a proton at point A and an electron at point B, at a distance of 1cm , separated by a screen.
If we remove the screen one would expect the particles to meet and clash somewhere near point A, but I read this never happens.
Can you explain why it's so and what exactly happen...
I expect you've heard about how the proton's weak charge has been measured directly:
http://www.sci-news.com/physics/science-weak-charge-proton-01391.html
Their findings so far are completely consistent with the standard model apparently.
So protons (and electrons) on Earth have now...
Homework Statement
2 protons in a Helium nucleus are separated by about 2x10^-15 m. Calculate the approximate magnitude of the strong force holding the 2 protons together.Homework Equations
Electromagnetic force equation?The Attempt at a Solution
Okay now I am thinking that the strong force is...
Homework Statement
Two protons with kinetic energies ##W_{k1}=4GeV## and ##W_{k2}=2GeV## colide and form new particles. What is the mass of newly born particles? Homework Equations
\begin{align}
W_{before}&=W_{after}\\
p_{before}&=p_{after}\\
W^2 &= {W_0}^2 + p^2c^2 \longleftarrow...
I've had this strange theory for a long time.
If a free floating proton has a tiny amount of mass, wouldn't excelating it to near C increase its mass or energy nearly infinitely?
If this is so, if we run a wire and fire electrons down its length let's say 100 times per second.
Then fire...
Hi :)
In this lecture (), susskind talks about attractive the force between two protons due to them sharing an electron and tunelling etc. He also describes how the electromagnetic force overwhelms this force when the protons are far apart.
What is the name of this force? And why do I...
So i was wondering if perhaps a atoms electrons protons and neutrons determine all of its characteristics, such as the hydrogen atom. having only one electron and one proton. it makes it turn into a liquid and solid very close together, and a gas anything above about -259.1°C. and the...
Hi all,
I would like to ask why only Protons were selected for collision in LHC project? Why not other fundamental particles?
When I was watching the programme on big bang by Michio Kaku and Lawrence Krauss, they were saying at the earliest instant of big bang, there were four forces...
(answered)Four Protons Are Fused Into Alpha Particle, Energy Released
Answered: I wasn't supposed to multiply by c2. Thank you ehild
I apologize in advance if I posted this in an incorrect format or in the wrong section. I read the rules and I believe this is the correct format/place...
Hey,
My question is with part (c) of the below:
I wanted to check that I had done this write as I struggle to determine the correct invariants for each frame... despite their invariance. So for the lab frame I had
\frac{\...
Homework Statement
LHC can accelerate proton beams to energies of 8Tev.
1. What is the centre-of-mass energy of two colliding protons?
2. What would be the beam energy needed if one wanted to reach the same centre-of-mass energy when colliding beam protons with protons in a target at...
Is it theoretically possible to have:
a) a helium atom with 2 protons, 2 electrons, and 2 antineutrons
b) a helium atom with 2 negatrons, 2 positrons, and 2 neutrons
c) a helium atom with 2 protons, 2 positrons and 2 neutrons
etc...
So I understand that:
Protons= 2 up quarks and a down quark... and
Neutrons= an up quark and 2 down quarks... and
Electrons are not made of quarks (so small!)
So my questions are:
1.) According the Heisenberg Uncertainty Principle, we don't know how many strings (according to string...
Homework Statement
At what distance between two protons are the electrical and gravitational forces equal?Homework Equations
electromagnetic Force = k(Q1*Q2/r^2)
gravitational Force = G(m1*m2/r^2)
Constants:
k = 9.0*10^9 (N m^2/c^2)
G = 6.673 × 10^-11 (m^3 kg^-1 s^-2)
Charge of proton...
(high school level physics btw)
apparently all baryons eventually decay into protons, so I was just curious to know if this was also true of anti-baryons?
I have two sources, one (school textbook) is telling me that ''all hadrons eventually decay into a proton'', whereas a few other people have told me that ''only bayrons decay into protons''. I want to know because I originally wanted to find out whether mesons decay into protons, and mesons...
I have been looking for experiments demonstrating neutron interferomerty with protons or electrons instead, and found non. Should there be any difference? I refer to experiments in which, for example, the Mach-Zehnder interferometer is cut from a single crystal.
I was wondering, how can both a proton and a neutron weight 1u?
An Up quark has a mass of 1.7–3.1 MeV (according to Wikipedia).
Down has a mass of 4.1-5.7 MeV.
Average Up: 2.4
Average Down: 4.9
If a proton is Up+Up+Down (2.4+2.4+4.9) it has a mass of 9.7 MeV.
A neutron is Down+Down+Up...
Hello. You'll have to excuse my spelling (If I spelled anything wrong), I'm from Sweden and even though I'm told to be good at English, I'm not an expert.
I literally just found this forum in my search for some kind of physics forum where I could ask the following question:
Are electrons...
Homework Statement
Piece of homework I am stuck on. I have to calculate the magnetic field required to maintain protons at 7Tev in the LHC which has a radius of 27 km. I also have to work out the cyclotron frequency as well.
Homework Equations
7 x 10^15 = mc^2/√(1-v^2/c^2) - mc^2...
In chemistry I remember learning that electrons and protons had equal but opposite charges but also that electrons were much smaller than protons. So how is it that something so much smaller can have an equal charge?
A stream of protons and electrons are shot horizontally (from the left edge of the page to the right) with a speed of 1.2 x 10^6 m/s. A magnetic field is oriented perpendicular to this motion (upward, out of the page) with a magnitude of 1.225 T.
What is the radius of the curvature and the...