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
The sun is powered by fusion, with four protons fusing together to form a helium nucleus (two of the protons turn into neutrons) and, in the process, releasing a large amount of thermal energy. The process happens in several steps, not all at once. In one step, two protons...
Dear all!
I am currently searching for experimental data on the sea and valence quark distribution of the proton together with the gluon distribution.
You find plenty of F^p_2(x) structure functions but no consideration on how it splits in terms of sea and valence quarks.
A big thanks for...
Stupid question (or maybe stupid asker), but I'm having a hard time finding an answer. Of course the movement of electrons (- charge particle) creates a magnetic field when moving steadily through a conductor but what about protons (+ charge particle)? Let's just imagine you have protons passing...
Homework Statement
A very thin beam of protons is injected at non-relativistic
velocities in a circular particle accelerator of radius R. The
mass m and the charge e of the proton are known. The initial
current in the accelerator is I and the total number of
particles is n. The magnetic...
Homework Statement
a 5.0 mm-diameter proton beam carries a total current of 1.5mA. the current density in the proton beam, which increases with distance from the center, is given by j=j(edge)(r/R), where R is the radius of the beam and j(edge) is the current density at the edge.
a) how many...
Homework Statement
A proton that is accelerated from rest through a potential of 20.0 kV enters the velocity filter, consisting of a parallel-plate capacitor and a magnetic field, shown below.
http://capa-new.colorado.edu/msuphysicslib/Graphics/Gtype61/prob09_velfilter.gif
The E-field...
I'm watching a documentary on the L.H.C and it struck me as odd when the narrator mentioned that the L.H.C. would be able to create the types of temperatures and pressures that were present at the big bang beginning.
I found it odd that two protons could recreate those conditions.
I've read that some protons in the Universe can have an energy of about 10^{20}eV, or in English, about a well-hit tennis ball. (The cosmic rays).
Is it possible for these rays to reach our brain? Or more precisely, what would happen if one gets hit by such an energetic particle?
P.S.: I...
Homework Statement
At very high temperatures (as in the early universe), the proton and the neutron can be thought of as two different states of the same particle, called the “nucleon”. (The reactions that convert a proton to a neutron or vice versa require the absorption of an electron or a...
Homework Statement
Two protons are moving directly toward one another. When they are very far apart, their initial speeds are 3.00*10^6 m/s. What is the distance of closest approach?
Homework Equations
The Attempt at a Solution
I really need help in question. I need to know how to...
Hi,
There are 3 Protons (P) that form a triangle.
distance PA-PB -->15mm
distance PB-PC -->20mm
distance PA-PC --> unknown
I have to calculate the last distance and the forces between the protons by using coulomb´s laws.
I tried to calculate the force between AB and BC:
F1=1.02 E...
Homework Statement
If a proton and an electron are released when they are 8.00×10e-10 m apart (typical atomic distances), find the initial acceleration of each of them.
Homework Equations
F=ma
F=kq1q2/re2
F=kee2/r2
The Attempt at a Solution
Since r=8x10e-10, I solved for the...
Homework Statement
1.Assuming that only gravity is acting on it, how far does an electron have to be from a proton so that its acceleration is the same as that of a freely falling object at the Earth's surface
2.Suppose the Earth were made only of protons but had the same size and mass it...
I'm curious about the nature of the evidence for three quarks -- two up and one down -- in the proton. I assume the data is derived from high energy scattering experiments, and looking at the angles and momenta of the scattered particles. But I don't see how, from such experiments, one can say...
I thought protons couldn't decay and I am pretty sure I've read it a few times as well but then with B+ Decay: p -> n + e + v
:confused:
Doesn't seem to make sense to me
1. In class we are discussing sub atomic particles and I approached my teacher with this question: If a electron is 2000 times smaller (roughly) than a proton, then the concentration of energy in the electron must be roughly 2000 times greater correct? She informed me that the charge to mass...
Homework Statement
In a certain accelerator, protons of kinetic energy 1.6 x 10^-7 J move round a circular path of diameter 2000m .
Calculate:
(a) the centripetal acceleration
(b) the mass
ans for a is 9x10^13 ms-2, for b is 1.78 x 10^-24 kg
Homework Equations
centripetal...
what causes the protons inside the atoms nucleus to stay together(next to one another), positive repels positive, therefore they should repel each other,
Homework Statement
Hey , I am a new member Here . I am having some diffuculties , i did one problem and still 1 problem i can't do it coz it seems very hard as i am new to gauss's Law
I am doing college physics II , protons are projected with initial speed of v0 = 9550m/s into a region in...
Hey guys this is my first post on Physics Forums, be gentle.
I've been wondering, what's the current explanation of why protons and neutrons have such very similar masses? Is this due to a difference in the up and down quark masses or is there something else going on here?
Thanks
Hello!
Does anyone have any ideas as to what would happen if 2 protons were accellerated to or just below the speed of light, fired (in a vacuum) in opposite directions to one another so that they would impact on each others side, not directly but rather in glancing fashion with a...
Homework Statement
A Cyclotron is accelerating proton, where the applied magnetic field is 2 T, the potential gap is 100 KV, then how much turn are required for a kinetic energy of 20 MeV...
(a) 300
(b) 200
(c) 150
(d) 100
I have been thinking about this for a while, and I am not sure about how I can visualize this.
Lets imagine that there can exist clouds of primordial matter, far away in space.
1. Can it be possible for a cloud to exist and be made out of strictly protons at 0 kelvins?
I don't...
At t = 0, 10^5 noninteracting protons are known to be on a line segment 10 cm long. It is equally probable to find any proton at any point on this segment. How many protons remain on the segment at t = 10 s?
Attempt at Solution
We can create a wavefunction for this scenario:
\psi(x, 0) =...
Quick question, regarding mass-energy equivalence (e=mc2) and matter creation.
Knowing that there are many concete visual examples of matter turning into energy using Einstein's equation, how do you use energy to create matter? If I'm not mistaken, I believe electron-positron pairs are...
Homework Statement
The problem states that two protons are aimed at each other with a certain velocity v. It asks what is the maximum electrical force they will exert on each other.
The velocity is given at 1000km/s. And that is everything given.
Homework Equations
KE = 1/2mv^2
F =...
[SOLVED] speed of two protons (I think an easy question)
Homework Statement
If you release two protons from rest 1.500nm apart, calculate the top speed, relative to you, that either proton will achieve.
Homework Equations
F=ma
ke^2/r=mv^2 where k=9.0e9 Nm^2/C^2 and e is the charge...
Styrofoam is a polymer containing carbon and hydrogen. Assume the formula is C8H8. How many molecules are in a 0.2 g styrofoam peanut? How many protons and electrons are in this peanut if it carries no excess charges? How many coulombs of positive and negative charge does this represent? If the...
1. I have ^{9}Be^{+}, ^{12}C, and ^{15}N^{+++} isotopes, and I need to find the total of protons, neutrons, and electrons.
A = Z + N, where A is the atomic mass number and Z is the number of protons and N is the number of Neutrons.
3. I know this is an easy question, I put it in physics because...
Homework Statement
Two protons that are very far apart are hurled straight at each other, each with an initial kinetic energy of 0.16 MeV, where 1 mega electron volt is equal to 1x10^6 multiply (1.6x10^-19) joules. What is the separation of the protons from each other when they momentarily...
[SOLVED] using electric force to calculate number of protons
Homework Statement
a hydrogen nucleus and a nucleus of an unknown atom are stationary, 5.0x10^-10m apart, the electric charge on the hydrogen nucleus is 1.6x10^-19C.
express the charge you have calculated for the unknown nucleus...
[b]1. Calculate the electric force between 2 protons in a nucleus that are 5*[10]^{-15} m apart. Compare this with the gravitational force between them.
Homework Equations
F(sub g)={GM(sub 1)M(sub 2)}/r^(2)
G=6.67*10^(-11) Nm^(2)/kg^(2)
Mass of proton=1.67*10^(-27)Kg
The...
[SOLVED] Cosmic Ray Protons
Homework Statement
Earth's atmosphere is constantly being bombarded with cosmic ray protons that originate somewhere in space. If the protons all pass through the atmosphere, each square meter of Earth's surface would intercept protons at at the average rate of...
Sorry if this is a really easy question, but in biology I don't normally deal with these matters, just confused about this.
Why is it that the mass of the electron is so much smaller than that of the proton or neutron, but the charge is similar to the proton (but opposite)? I'm assuming it has...
Homework Statement
A small drop of water is suspended motionless in air by a uniform electric field that is directed upward and has a magnitude of 8450 N/C. The mass of the water drop is 3.80 10-9 kg.
(b) How many excess electrons or protons reside on the drop?
Homework...
On another recent thread a claim was made about the size of an electron being particularly small (maybe a point). I was unclear what that means. I thought that an electron was rather "smeared" in an orbital or wavefunction.
So does the "size" of the electron refer to its size after the...
[SOLVED] Is it the protons or electrons that are responsible for an element's propert
On a chemistry test I took, there was a question that asked "What subatomic particle is responsible for an element's physical and chemical properties"?
I picked the "proton" as the answer choice, but the...
Dr. A. Chou of the Auger Ultra High Energy Cosmic Ray detector announced today that the last three years of partial information has been analysed to show at the 95% confidence level, UHECR's are caused by protons from Active Galactic Nuclei.
Dr. Chou presented his data to the conference on...
Homework Statement
I have to protons coliding - they have same magnitude of velocity and momentum and they collide head-on:
p + p -> p + (p + p_) (the "p_" is an anti-proton).
I have to find the minimum combined kinetic energy of the two protons for this process to run.
The Attempt at...
Homework Statement
In a fusion reaction, the nuclei of two atoms join to form a single atom of a different element. In such a reaction, a fraction of the rest energy of the original atoms is converted to kinetic energy of the reaction products. A fusion reaction that occurs in the Sun...
Homework Statement
Two protons that are very far apart are hurled straight at each other, each with an initial kinetic energy of 0.16 MeV, where 1 mega electron volt is equal to 10^6*(1.6*10^-19) joules. What is the separation of the protons from each other when they momentarily come to a...
Homework Statement
state the number of protons electrons and neutrons of these:
Magnesium-25
Cu-65
Homework Equations
protons is the same as atomic numbber, same with electrons. NEUTrons is atomic number - atomic mass
The Attempt at a Solution
Magnesium-25 Cu-65...
Hello guys, can you help me on this question:
What accounts most for the spin of protons? I think the quarks only contribute a few percentage for the spin, but I'm wondering if there are new discoveries about the main cause of proton spin
thx!
Homework Statement
A proton is confined in a uranium nucleus of radius 7.41 fm. Determine the proton's minimum kinetic energy K less than or equal to delta K according to the uncertainty principle if the proton is well approximated by a Gaussian wave packet confined by the nuclear diameter...