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


by KnowledgeIsPower
Tags: attract, electrons, negative, positive, protons
KnowledgeIsPower
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#1
May14-04, 02:22 AM
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Despite studying chemistry i've never actually been given this information, any explanations/theories that could possibly explain why?
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ShawnD
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May14-04, 03:41 AM
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Are you asking why protons are different from electrons, or are you asking why we decided the electrons were negative instead of positive?

I don't know why the protons would be positive and electrons negative; it's just one of those things you have to accept.
As for why electrons are negative instead of positive, that's just the way it was decided. Would it have made any difference if people decided electrons were positive and protons were negative? Obviously it wouldn't.

Why they attract? The general rule is that everything wants to maintain equilibrium and have the lowest potential difference. If you open the door to your house during winter time, heat doesn't enter your house to make the difference in temperature greater; heat leaves your house to make the difference in temperature 0. Positive and negative are a lot like hot and cold; they are opposite, and they cancel each other. Positive and negative will be attracted to each other so they can have the smallest difference of charge possible.
enigma
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May14-04, 04:07 AM
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'positive' and 'negative' are nothing more than two arbitrary names given to describe a phenomena. The original naming convention was assigned by Ben Franklin when he was doing some sort of experiment. They just as easily could have been called 'up' and 'down' (which have since been given to quarks to denote certain characteristics), or 'black' and 'white', or 'fish' and 'bird'.

KnowledgeIsPower
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#4
May14-04, 06:40 AM
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Why are protons positive. Why are electrons negative? Why do they attract?


I know what they are and it doesnt matter why they were named like that, but what makes their charges different? What makes one 1, and the other, -1.
arildno
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May14-04, 11:24 AM
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Well, you could give a limited explanation by regarding protons and electrons from the quark level.
On this level, the explanation of the difference in the electron/proton charge (and, for that matter, the neutron's non-charge) is that electrons and protons are constituted from different sets of quarks (i.e. quarks with different charges)
I believe that the proton is constituted by 2 quarks with 2/3 charge units each, along with one quark that has -1/3 charge unit (2/3+2/3-1/3=1).
The electron, I believe, consists of 3 -1/3-quarks (-1/3-1/3-1/3=-1)
The neutron (2/3-1/3-1/3=0) (I think..)

However, your question can be said to be explained only by pushing back the fundamental fact of nature (that there exist opposite charge types associated with certain particles) onto a deeper level.
Explaining that fact of nature would have to be "explained" by other facts of nature, and so on..
jcsd
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May14-04, 02:04 PM
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aridlino, you're right about the proton and the neutron, but the electron is not a baryon or indeed any kind of hadron, it's a lepton and therfeore an elementary particle in it's own right (i.e. it's not made up of quarks).
arildno
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May14-04, 02:13 PM
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Good that a person with real knowledge of elementary particles corrected me on this; I felt the ice cracking beneath my feet when I posted it..
jcsd
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May14-04, 02:19 PM
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I wouldn't say I had a great knowledge on elemntary particles, I've only gleaned a little technical knowledge in this area, anyway here's a nice list of all the subatomic particles, which includes their classification and quark content:

http://hyperphysics.phy-astr.gsu.edu...es/parcon.html
Imparcticle
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#9
May14-04, 08:22 PM
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proton is constituted by 2 quarks
They are constituted of 3 quarks.

A neutron is constituted of 3 quarks also. Unlike the proton which is contituted of 2 up quarks and 1 down quark, the neutron is composed of 2 down quarks and 1 up quark. Does the sum of up or down quarks determine the electrical charge of a [subatomic] particle?
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May15-04, 01:27 AM
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Quote Quote by KnowledgeIsPower
I know what they are and it doesnt matter why they were named like that, but what makes their charges different? What makes one 1, and the other, -1.
Only thing I can think of to explain it is: that's the way the universe is. The particles have a property that attracts and repels based on something which we have arbitrarily defined as a "charge". The "charge" behaves according to certain rules, and it is best described in terms of positive and negative terms.
KnowledgeIsPower
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May15-04, 03:49 AM
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Quote Quote by enigma
Only thing I can think of to explain it is: that's the way the universe is. The particles have a property that attracts and repels based on something which we have arbitrarily defined as a "charge". The "charge" behaves according to certain rules, and it is best described in terms of positive and negative terms.
It's difficult to understand what charge is, why is is created and why one type of charge is attracted to another. Of course, you could go on asking the why questions forever..
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May16-04, 01:04 PM
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In order for neutral atoms to exist, the two components, nucleus and shell, have to be of opposite sign. This could happen if the nucleus contained antiprotons and the shell antielectrons, or it could happen the way we actually experience, with protons and electrons. And the reason we have this is that antiparticles appear to be extremely rare in the universe. And that is a BIG puzzle because the particles and antiparticles should have been equally produced in the early universe
Imparcticle
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May17-04, 05:14 PM
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Do quarks have a negative charge because their spin is opposite to the designated opposite (positive) spin?
Janitor
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May17-04, 11:42 PM
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I don't know that this adds anything useful to the discussion, but I will note that charge is classified as an extensive variable (meaning its net value is proportional to the quantity of substance in the system, taking signs into account if both types of charge are part of the system). Other examples of extensive variables are energy, volume, and momentum. The other class of physical variable is the intensive type, temperature being the prototypical example.

Charge is also a relativistic invariant. The charge of a particle is independent of its speed relative to the observer.

In electrostatics, the divergence of the electric field intensity is proportional to the electric charge density. In a small region of space where the charge is positive, the lines of electric force can be thought of as pointing away from that region. In a small region where the charge is negative, the lines of electric force can be thought of as pointing toward that region. Since vectors (electric field intensity vectors in the case at hand) pointing in opposite directions are considered the negative of one another, it is consistent that positive and negative signs are applied to the two varieties of charge found in nature.
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May17-04, 11:49 PM
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There is only one type of carrier of force between electric charges, the photon.

If the universe was such that electric charge came in three varieties instead of two, we couldn't use positive and negative signs. A more complex algebra would be needed. For instance, it might turn out that the charge algebra would be SU(3), in which case there would be eight different types of force carriers instead of one.

Nature does in fact have a type of 'charge' that comes in three and exchanges eight types of bosons: the so-called color charge of chromodynamics.
quartodeciman
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#16
May18-04, 01:12 PM
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Benjamin Franklin decided there was just one kind of electrical fluid in nature. He opined that wool rubbing wax took electricity away from the wax. The wool ended up with a surplus of electricity and the wax ended up with a deficit of electricity. Therefore, he described the surplus as + and the deficit as -, in analogy to credits and debits of money. This somehow became the usual designation.

The choice became questionable in the nineteenth century. In electrolysis experiments with charged electrodes in beakers of metal salt solutions, metal would deposit on the - electrodes but not on the +. Odd that the deficit electrical part would get more (interesting) activity than the surplus electrical part. This was resolved by Faraday (I think) proposing that metal atoms already have surplus electricity and naturally migrate to the - electrode, being mobile in the solution. He called charged atoms "ions". He found that the quantity of deposited metal could be predicted accurately by current times time.

Later in the nineteenth century, cathode rays were produced and studied assiduously. If the cathode (- terminal) of a cathode ray tube is heated, then cathode rays are produced (a glow occurs). If the anode (+ terminal) is heated instead, this doesn't work. By this time probably nobody cared about which ought to be called + and which ought to be called -. There are cations (+ charged) and there are anions (- charged). The important thing is that the product Q1Q2 is positive when the charges are both + or both - (which means a repulsive force) and the product is negative when the charges are +- or -+ (which means an attractive force).

It must have also set people back in their chairs when Rutherford, Geiger and Marsden in 1911 showed the electrical charge distribution within the space of atoms. Almost all of the space is where the - charged electrons dwell*. All of the + charge (and also the main part of the atomic mass) is concentrated into a very tiny part of of the atomic space, what we call the "nucleus".

*A LITTLE CORRECTION: They thought that some electrons were in the nucleus too. The neutron had not been conceived yet.
The Bob
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#17
Jun21-04, 12:52 PM
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I am only 15 so what I have to say may not be complicated but it should help. I do apologise for any misspellings and the wrong use of language now.

Now I know about quarks and orbitals so it is back to basics. I know that the 1s orbital level contains one up spin and one down spin electron. Therefore I can safely say that the spin of the subparticles have nothing to do with the charges.

Now it is the norm to say that a proton has a +1 charge and an electron has a -1 charge and neutrons have no charge (0). Each subparticle is made of 3 quarks however I do not know the different combinations that make it so the subparticles have different charges. Logic would say that a proton would have two up quarks and one down quarks and an electron would have one up quark and two down quarks. This leaves the neutron. Does it have three up quarks or three down quarks?

Another point that I believe is need to be stated is the fact that both a proton and a neutron have a mass of 1 and an electron has a mass of 1/1840 but the number of electrons and protons are the same. Therefore the overall charge of all atoms should be positive because there is more positive mass and so more positive charge (like gravity on different masses (on the ground or it will not work the same (LOL))). However atoms are neutral (unless they are ions) so although it makes sense why the charges balance out it does not make sense in terms of mass.

Yet another point. Why doesn't the protons and electrons attract each other? It should be that they do. Look at magnets. The south pole of one magnet and the north pole of another magnet attract each other. It was put down to the 'Colossians Affect'. This was a theory that the subparticle were held apart by another force that scientists could not find. They thought this was too religious and discarded it. It is in the bible though that everything is held by the hand of God and that if he were to release that everything would be in ruins.

The easiest why to answer all of these questions would be that there are antisubparticles (suggested by selfAdjoint), but there is not much proof for any anti-substains (e.g. anti-matter, anti-particles etc.). It is likely to be a that-is-how-the-universe-is question and answer scenario, but if people continue to put up suggestion it might fall into place and I may think of something.

Anyway hope this was useful in some way, even if it is to prove me wrong (as the best way to prove anything is to disprove everything else).

Hope I can be as intelligent as all of you one day.

The Bob (2004 )
selfAdjoint
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#18
Jun21-04, 02:18 PM
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Up quarks have a charge of +2/3 (positive charge numerically 2/3 of an electron's charge). Down quarks have a charge of -1/3. Proton is 2 ups and a down as you say making 4/3 - 1/3 = 1. Neutron is 2 downs and an up, -2/3 + 2/3 = 0. Notice the the neutron has a magnetic moment - it will turn in a magnetic field - showning that it's components are cherged even if the whole particle isn't.

Protons and electrons do attract each other by opposite electric charge. And protons and protons repel each other by having the same charge. But in both cases there are other things happening that prevent the obvious result of electrons spiraling into the nuclei, which then explode.

First of all note that sidewise motion can frustrate attraction. The moon and the earth attract each other; why doesn't the moon then fall down on us? In fact the moon is constantly falling, but it also has a sideways speed, so that when it falls to point a it has also moved away from the original line to earth and its acquired velocity is partly tangential,, and so on around the orbit. Electrons do this too, although they do it quantum fashion. And as for exploding nuclei, they are kept together by the strong force, which has a different kind of charge named color, and which is able to overcome the electrical repulsion.


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