# Why are protons positive. Why are electrons negative? Why do they attract?

Just like many questions regarding gravity, it seems difficult to explain exactly why one thing can attract another through thin air.
My entire chemistry education has basically been founded on positive and negative attracting, but i don't really know why they attract.
Just an amusing point.

KnowledgeIsPower said:
Just like many questions regarding gravity, it seems difficult to explain exactly why one thing can attract another through thin air.
My entire chemistry education has basically been founded on positive and negative attracting, but i don't really know why they attract.
Just an amusing point.

Can't help then? I would like to know to my post.

I still would like to know, however, if the neutrons hold the protons together so they do not fly out by their repelling charges. Do the neutrons hold the protons together?

The Bob said:
I still would like to know, however, if the neutrons hold the protons together so they do not fly out by their repelling charges. Do the neutrons hold the protons together?

Hmm, good question, it seems to be something to do with the neutrons from what i've read on the web but i've struggled to find an exact answer.
If nobody can come up with a reason by tomorrow morning i'll ask my chemistry professor tomorrow afternoon.

loseyourname
Staff Emeritus
Gold Member
mizzuno said:
If these particles are attracted to one another, shouldn't electrons be pulled into the nucleus? I gather the reasoning is because of the strong force? If thats the case i need to understand this "strong force" better..

Mizzuno

This question is actually addressed in the Feynmann lectures, which are linked to in the physics napster thread in the General Physics forum. The answer is:

What keeps the electrons from simply falling in? [The uncertainty principle]: If they were in the nucleus, we would know their position precisely, which would require them to have a very large, but uncertain, momentum, i.e., a very large kinetic energy. This would cause them to break away from the nucleus. They make a compromise: they leave themselves a little room for this uncertainty and then jiggle with a certain amount of minimum motion in accordance with this rule.

It wasn't really the answer I was expecting. I was previously under the impression that the uncertainty relations were only an expression of our own limitation as subjective observers of a subatomic event, but apparently they are actually an expression of a fundamental principle governing the behavior of small particles. If you're curious, the relation used here is:

$$\Delta x \Delta \rho \geq \frac{h}{2\pi}$$

Where
x = the position of the particle,
$\rho$ = the momentum of the particle, and
h = Planck's constant

KnowledgeIsPower said:
If nobody can come up with a reason by tomorrow morning i'll ask my chemistry professor tomorrow afternoon.
Quality. Cheers . And maybe about my other point (about the forces that an electron and a proton apply as an electron is so much smaller).

loseyourname
Staff Emeritus
Gold Member
Charge is independent of mass.

KnowledgeIsPower said:
If nobody can come up with a reason by tomorrow morning i'll ask my chemistry professor tomorrow afternoon.

Quality. Cheers . Maybe you could ask about my other point (about the different mass of the protons and electrons).

The Bob said:
And what about my point on the different mass sizes of the negative and positive subpartilces? Does that not matter to the overall charge then (as it makes sense to me that all atoms should be positive (but I know they are not)).

Sorry my computer just caught up.

loseyourname said:
Charge is independent of mass.

I dunno why but you saying that makes more sense then when it was in my head

Cheers loseyourname

loseyourname said:
$$\Delta x \Delta \rho \geq \frac{h}{2\pi}$$

Where
x = the position of the particle,
$\rho$ = the momentum of the particle, and
h = Planck's constant

What is this for and what is Planck's Constant?

loseyourname
Staff Emeritus
Gold Member
Planck's constant is $6.626~\textrm{x}~10^-34 J \cdot s$.

If you rework the relation shown, you can get

$$\Delta \rho \geq \frac{h}{2\pi \Delta x}$$

If the electron's position is known with near certainty (which would be the case if it were to collapse into the nucleus), then $\Delta x$ approaches 0. So let us take the limit of the relation as $\Delta x \rightarrow 0$:

$$\Delta \rho \geq \lim_{\Delta x \rightarrow 0}\frac{h}{2\pi \Delta x}$$

We can see that

$$\lim_{\Delta x \rightarrow 0}\frac{h}{2\pi \Delta x} = \infty$$

It should be clear that not only can $\Delta \rho$ not be greater than or equal to $\infty$, but it cannot even approach this value if $\Delta x$ approaches 0. Stated simply, the momentum of a particle cannot be close to infinity if its motion is nearly zero. Because of this, the electron must remain somewhere in the electron cloud surrounding the nucleus.

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I understand about the protons and the neutrons, now (thanks ), but what about the electons? Having thought about it, logically it should be three down quarks as that would be -1/3 -1/3 -1/3 = -1. Is this right? Does it have three down quarks or is it three up quarks? (Or have I missed the point?) Or is it just something I have to execpt?

No.... Electrons are leptons, which, as far as we can tell, are fundamental particles. Nothing makes them up. (No doubt some string theorist will butt in here to say I'm wrong, but as far as I know, it has not been observed.) And the quark charges are only part of the thing. The strong force works by colour charges, and other such complexities, which forbid certain combinations.

And what about my point on the different mass sizes of the negative and positive subpartilces? Does that not matter to the overall charge then (as it makes sense to me that all atoms should be positive (but I know they are not)).

No. Why should it? A ton of feathers still weighs a ton.

Neutrons holding protons? Sort of, yes. Within the hadrons, the quarks are held together by the strong force, which is mediated by particles called gluons. (The theory behind this is Quantum Chromodynamics, which is still kinda sketchy.) Some of this force leaks out, and this is what holds the neutrons and protons together. Essentially.

FZ+ said:
No.... Electrons are leptons, which, as far as we can tell, are fundamental particles. Nothing makes them up. (No doubt some string theorist will butt in here to say I'm wrong, but as far as I know, it has not been observed.) And the quark charges are only part of the thing. The strong force works by colour charges, and other such complexities, which forbid certain combinations.

Sorry FZ+ but in post 22# I said that I got it explained to me although I will have to research this string theory. I have heard it about 50 times now.

FZ+ said:
No. Why should it? A ton of feathers still weighs a ton.

What I mean is that an atoms (lets take Lithium) will have 3 protons and 3 electrons. The protons have a mass (total) of 3. The electrons have a mass total of 3/1840. So I thought that the mass would affect the amount (or strength) of charge and make the atom positive other all. I was wrong though but I don't know why, unless it is simply that charge is independent of mass (said by loseyourname) and that I must except it. *EDIT* Just though of the old capacitors and the newer ones. They do the same job and have different masses. Sorry.

FZ+ said:
Neutrons holding protons? Sort of, yes. Within the hadrons, the quarks are held together by the strong force, which is mediated by particles called gluons. (The theory behind this is Quantum Chromodynamics, which is still kinda sketchy.) Some of this force leaks out, and this is what holds the neutrons and protons together. Essentially.

Right. I will remember this. Cheers

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The answer was that nobody knows the real reason at the minute, though it seems to be something to do with binding energy, which is created when protons and electrons combine to form a neutron.

My personal theory is that as protons and electrons combine, neutrons are polar. As there are usually more neutrons in an atom than protons they are arranged much like hydrogen bonds between water molecules, in that like charges from the negative ends of neutrons will attract protons. If there is a greater number of neutrons surely they will hold the protons in the center in a kind of lattice, if arranged correctly.

If anyone here has anything to add, or any possible problems with that theory i'd be interested to hear it.

But that's just my idea, it's not concrete and i certainly haven't done any experiments to 'prove' it.

KnowledgeIsPower said:
The answer was that nobody knows the real reason at the minute, though it seems to be something to do with binding energy, which is created when protons and electrons combine to form a neutron.

My personal theory is that as protons and electrons combine, neutrons are polar. As there are usually more neutrons in an atom than protons they are arranged much like hydrogen bonds between water molecules, in that like charges from the negative ends of neutrons will attract protons. If there is a greater number of neutrons surely they will hold the protons in the center in a kind of lattice, if arranged correctly.

If anyone here has anything to add, or any possible problems with that theory i'd be interested to hear it.

But that's just my idea, it's not concrete and i certainly haven't done any experiments to 'prove' it.

If the neutron is polar it must have a positive end (or it will not be neutral). Therefore the force acting on the electrons is even higher than just protons attracting them. The idea is good but seems unlikely although the idea of the polars is very good (as a neutron is made of an up (positive) quark =2/3 and 2 down (negative) quarks = -1/3 - 1/3 = -2/3, which are equal like a magnet).

Can't really fault it properly but it is good.

The Bob said:
If the neutron is polar it must have a positive end (or it will not be neutral). Therefore the force acting on the electrons is even higher than just protons attracting them. The idea is good but seems unlikely although the idea of the polars is very good (as a neutron is made of an up (positive) quark =2/3 and 2 down (negative) quarks = -1/3 - 1/3 = -2/3, which are equal like a magnet).

Can't really fault it properly but it is good.

Yes, but i would suggest that the neutrons are binded to the protons with their positive ends facing away from the protons, and towards the electrons, reducing repullsion on the protons and even increasing attraction on the electrons.
Perhaps also neutrons are situated evenly at intervals on the 'outside' of a centralised complex of proton/neutrons. If they were situated at regular intervals then surely repullsion away from the neutrons could be the same for all the sides on the protons and they would be repelled towards the center, possibly negating the repullsion they would exert on each other.

reilly
The plain fact is, sad to say, nobody has a clue about the fundamentals of electric charge, nor mass -- that is, we do not know why charges are either + or - Ne, or + or - e/3, where e is the electron's charge and N is an integer, nor do we know the why of the electric/ magnetic forces. But given the usual assumptions, we can do wonders in explaining chemistry, radar, atomic spectra, superconductivity, and so on. The same goes for masses -- although the standard theory does give some clues.

In his great work on Hydrogen, Bohr said: "If, the electron is confined to various discrete, STABLE orbits, then, ....". He subsequently derived the formulas for the spectra of hydrogen. Why stable orbits? Who really knows? But, the mature quantum theory of atomic systems based on the Schrodinger eq. yields Bohr's stable atomic orbits, which we now call stationary states. Why does QM work? Who knows? But, indeed, QM does work -- some have called QM the most tested of scientific theories.

The end of science is nowhere in sight.
Regards,
Reilly Atkinson

(The Kaluza-Klein 5-dimensional relativity, the mother of "folded dimensions", does predict quantized charge, but the details don't match reality."

The answer was that nobody knows the real reason at the minute, though it seems to be something to do with binding energy, which is created when protons and electrons combine to form a neutron.

No. Binding energy is just a number we calculate. It is just an observed value. It has nothing to do with how it really works. Best theory, last I looked, is still Quantum Chromodynamics. People used to think the neutron attracted protons by electrostatics, but experiments with particle accelerators and so on have shown that to be false. The attraction is just too strong, and worse, does not diminish the way electromagnetics is known to diminish with increasing distance. We *need* the strong force.

Proton is positive beaucouse the first subatomic particle that was discovered is positivly charged, and that particle was named proton. It name comes from latin word PROTOS which means the first and the most important. When other particles were discovered they were given names that suite them the most. Electron was given name on Greek language ELEKTRONION which is a kind of rock. It was taken that sign of proton was +1 and of electron -1.

Electron was given name on Greek language ELEKTRONION which is a kind of rock.

IIRC, it comes from Electrum, which is an archaic name for amber - because early static electricity was made by rubbing amber. This is also where terms like electricity came from.

FZ+ said:
IIRC

IIRC? Another term I do not know. What is it please?

If I Remember (or Recall) Correctly

FZ+ said:
If I Remember (or Recall) Correctly

Cheers

Well I came across this forum while studying electricity for my Aviation Maintenance classes and would like to put in my 2 cents:

Quatro.., is right:

When Benjamin Franklin made his conjecture regarding the direction of charge flow (from the smooth wax to the rough wool), he set a precedent for electrical notation that exists to this day, despite the fact that we know electrons are the constituent units of charge, and that they are displaced from the wool to the wax -- not from the wax to the wool -- when those two substances are rubbed together. This is why electrons are said to have a negative charge: because Franklin assumed electric charge moved in the opposite direction that it actually does, and so objects he called "negative" (representing a deficiency of charge) actually have a surplus of electrons.

By the time the true direction of electron flow was discovered, the nomenclature of "positive" and "negative" had already been so well established in the scientific community that no effort was made to change it, although calling electrons "positive" would make more sense in referring to "excess" charge. You see, the terms "positive" and "negative" are human inventions, and as such have no absolute meaning beyond our own conventions of language and scientific description. Franklin could have just as easily referred to a surplus of charge as "black" and a deficiency as "white," in which case scientists would speak of electrons having a "white" charge (assuming the same incorrect conjecture of charge position between wax and wool).

However, because we tend to associate the word "positive" with "surplus" and "negative" with "deficiency," the standard label for electron charge does seem backward. Because of this, many engineers decided to retain the old concept of electricity with "positive" referring to a surplus of charge, and label charge flow (current) accordingly. This became known as conventional flow notation.

FUNNY how those kind of things happen.