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Properties of atoms

  1. Aug 15, 2007 #1
    Hi! This will be my first post :P Ever since I was a little kid I've wondered what exactly an atom is. Apparently these atoms have smaller particles like electrons, neutrons and protons which have mass (I am assuming its proven? If not I want proof!) and the nucleus of the atom is held together with nuclear forces (right?). I know the basic stuff about atoms, but I want to know exactly why the protons have a positive charge and electrons have a negative charge. I know that the proton and neutron have the + & - charge simply because its convention and physically proven, but I want to know specifically how the charge is created? Also, abiding by the laws of thermodynamics for now, I also want to know how the atom gains the energy to create charge and the nuclear force that holds the atom together ( I am assuming the energy comes from external forces like sunlight in photosynthesis). If you guys have any information on the properties of atoms please share them with me as I need basic knowledge before I move on.
  2. jcsd
  3. Aug 15, 2007 #2


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    Welcome to PF, Fullperson.
    The magnitude of forces is determined by the quark components of the hadrons such as protons. The positive/negative and associated number are simply human constructs that give us a standard system of measurement. As far as I know, the +1/-1 for protons and electrons was established before anyone realized that there were smaller particles involved. It would make more sense to me if the quarks had full charges rather than fractional.
  4. Aug 15, 2007 #3


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    Why the proton and electron have the same magnitude charge is one of the big mysteries.
    Protons are made of 2up and 1down quarks, Ups have a charge of +2/3, downs have -1/3 so overall you have +1.
    How the electron, which isn't made of quarks, has exactly the same charge isn't known. Especially tricky as we believe that electrons and quarks aren't made of anything smaller.

    The strong nuclear force holds the protons together, since they are positively charged they would fly apart. The electrical force holds the negatively charged electrons near the positively charged nucleas, qunatum mechanics stops them 'falling' in.
    ps - It doesn't take any energy to create equal and opposite charges.
  5. Aug 16, 2007 #4
    LOL I had to use wikipedia 4 times for definition searches. Ok, so I am assuming that the combination of quarks bring the charge right? (Like protons have the +1 charge because of the two ups and one down). If this is true then neutrons should be a triplet of one up and two downs to form a net charge of 0. Is each up quark the same as another up quark, if this is true then if you break apart a proton and a neutron, one of the downs in the neutron could switch with another down in the proton, creating a proton and an electron except with switched down quarks (should work, the charges are the same and the triplets are equal).

    Also because I'm all sugared up by honey nut cheerios I have a hypothetical situation for you guys:

    A proton and a neutron go through some kind of break down (possibly a huge collision). The following quarks that show up are: 3 ups 3 downs
    (2ups and one down from proton and one up and two downs from the neutron)

    As a result the charges of the quarks are: 2/3, 2/3, 2/3,-1/3, -1/3, -1/3

    6/3 -> two +1 charges (two protons).... -3/3 -> one -1 charge

    is it possible?
    is the electron made of quarks?? (I know you guys said impossible but prove to me plz XD)

    Further, if the quarks are the rascals that are have the charge, why & how would they have them? I feel like in 2010 people will be like ooOO there are new A, B, C ect.. particles that make up those quarks that have the charge! :D In fact, also prove to me that the quarks have charge, have we measured them?

    TY you guys for being so patient you guys are awesome!
  6. Aug 16, 2007 #5


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    Strangley it isn't possible to have a quark on it's own, a free quark, they can only exist in combinations.
    The really odd thing is that quarks and electrons are about as different as it is possible for real world particles (ie fermions) to be - and yet add up to the same charge!

    It's seen by many as one of the failings of the standard model ( ie our current knowledge of particles) that there seem to be just more and more particles and no simple underlying model beneath them. It's a bit like chemistry before the discovery of the periodic table, when everythng suddenly fell into place. Of course there is no reason to beleive the universe owes us a simple explanation, there may just be an infinite level of smaller and smaller particles.
  7. Aug 17, 2007 #6
    hmmm... I am glad that others think as I do. Perhaps we made made an incorrect assumption or measured one of the properties about the fundamental particles incorrectly? Does anyone else think that somewhere along the road we made a mistake and we are driving further away from reaching the real reason for charge by trying to cover up problems with more possibly false theories? O well, back to wikipedia...

    Hey! Does nature say that quarks can not be found by themselves? Although I am not able to understand the math, I am assuming that the confinement property of quarks (they can not be found alone) is just a property that we believe. But wait a minute...that would mean that if quarks were to smash into each other and form new particles there would have to be instantaneous creation of new particles so that no quark would be found alone... That doesn't make any sense!! I looked up quarks on Wikipedia and it states that they have mass... idk how they measured that but apparently its been proven? All I know is that any particle with mass can not just instantaneously
    break apart and reform!!! Possibly there is a measurement error? Or maybe the theory or my logic is flawed...

    Further, does nature say that quarks have to be found in triplets to form hadrons?

    p.s. someone teach me calculus lol (seriously, I can't locate possible problems with theories by looking at underlying mathematics unless I understand the logic behind them... )
  8. Aug 19, 2007 #7


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    It's more the case that our models and therefore our understanding dictates that quarks have to be found in triplets to form baryons.
    See - http://hyperphysics.phy-astr.gsu.edu/hbase/particles/quark.html



    See discussion of hardons and baryons here -

  9. Aug 24, 2007 #8
    oookay... I finally got myself to read through the sites. However, I am still puzzled by how specifically we found the quarks. To elaborate, I am confused as to how the particle accelerators are used and how we extract the data form these tests (how do we give analysis)... and is it possible for me to examine the lab data?

    I also have another question, I am really annoyed about the pion and the Rho vector Meson. Apparently they have the same combination of quarks (one up and one anti-down) HOWEVER, they have different masses! (139.6 MeV vs. 770 MeV). How is this possible, unless the rest of the mass is invested somewhere else, or is the arrangement of the quarks in these two that cause the mass change??

    I'm also still annoyed that we still have not found out the reason for charge of a particle besides the postulate that quarks have integer charges. I mean seriously people, how can we say charge is made up of electrons because they are made up of quarks that have charge? Its like charge is a circular definition! :/
  10. Aug 25, 2007 #9


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    Electrons are not composed of quarks. They're elementary particles. The heavy particles such as protons and neutrons are quark-based.
  11. Aug 25, 2007 #10
    oops my bad, then why do electrons have charge?

    I fear the answer, "because we defined it as so..."

    ps, I still don't understand the pion and Rho vector Meson problem, would be helpful if someone could elaborate why a mass difference exists
  12. Aug 25, 2007 #11
    Your curiosity is admireable, and your questions are relevant. However, I think you have somewhat high expectations to this forum's capabilities.

    Electrons are said to have charge because it has been observed that they do. However, nothing has been observed that suggests that electrons posses an inner structure - i.e., people have pretty much no idea *why* they have charge. As you've probably gathered from the responses in this thread, it is even more puzzeling that the charge fits those of other particles so well.

    Any answer to the question "why" will either involve the assertion of an equally explenation-demanding cause, or it will be in the form of "because it is" or equivalent. Physical models cannot be proved in the way that one may prove e.g. a mathematical statement. They can only be disproven through inconsitency with observation.

    PS:Are you studying science or do you have plans of eventually doing so? Given your inquisitiveness into the matters of nature, considering such a pursuit could potentially be very rewarding.
  13. Aug 27, 2007 #12
    Ok, you have assured me what I feared :P Perhaps there is another way to view the atom, possibly by describing them by forces. Hey w8 a minute! quarks are basically "imaginary particles of under the influence of force carrying a charge which will cause...force" So are electrons and protons and...neutrons? If this is true, then technically we are describing atoms and therefore mass via forces. ooo I smell a force, energy, mass relationship! Time for some serious basics, observe the forces involved and not focus on the projected masses which we observe when we smash quantas (did I use this word right?) of force together? W8, it can't be force, it has to be energy since force is an interaction? That would mean we would have to define atomic particles by their energies rather than their masses and then define the forces as the interaction between the quantas of energy. Somewhere in this relation will be the creation of mass? Ahh I'm confused, bring me the basic measuring tools and possibly some new tools to observe energies of particles stat!

    on another note,
    I might go into business because my parents are bugging me, but I'd live a life of regret... If you guys know any jobs that would pay lots of money and allow me to complete experiments that I so badly want to do plz tell me lol. About the question of studying science, I am going to be a junior in High school and I don't know enough math to examine the theories as I want, so I am not really studying science as I'd like.
  14. Aug 27, 2007 #13


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    there is no experiment that gives info that the electron is a composite system of quarks as in the nucleons. The form factor is unity = charge distribution is point like = no spatial extension. Hence it can not be made up of quarks. Maybe something else, much much smaller. We do not know that yet.

    How much math and physics at collage level have you studied? You seem to be very courious, why not do a career as particle physicist ? =)

    And you might want to consider another source of information than wikipedia sometimes, we will be delighted to give you books etc that fits your background knowledge.

    And we cannot always keep continue to ask "why" why" etc, we will eventually face the real fundament of nature. Why is the speed of light in vacuum = c ? etc. Sometimes nature is nature... Imagine that you were God, creating the universe (and do a comparison with a mathematican, creating a system, he does axioms and theorems). You set up fundamental constants, and forces, and laws.

    And how why know that quark exists comes from high energy scattering of electrons of nucleons.

    And the
    "I also have another question, I am really annoyed about the pion and the Rho vector Meson. Apparently they have the same combination of quarks (one up and one anti-down) HOWEVER, they have different masses! (139.6 MeV vs. 770 MeV). How is this possible, unless the rest of the mass is invested somewhere else, or is the arrangement of the quarks in these two that cause the mass change??"

    They have different masses due to a spin-coupling term in the mass-equation. (it matters if they have parallell or anti-paralell spin) if I remember right.
    Last edited: Aug 27, 2007
  15. Aug 28, 2007 #14
    OOO yea, plz recommend some books to me :P I'm especially interested in how the physicists derived the equations forming the theories and postulates of atoms. I'll take just about everything I can understand (I'm going to be a junior at my highschool taking precalc math so anything above that will make me go "huh?"

    On another note, there's a spin coupling term? Is this spin an abstraction that we created or is it real? Nvm, I'm sure I'll understand it in the books you guys provide me.

    Its very interesting that electrons are not made of quarks yet have charge... Could someone compare mass and total energy and charge within the electron to the quarks... I'm tempted to think that electrons and quarks might be similar or be made of an even smaller possibly similar particle?. I have a feeling theres a connection between the quark and the electron, with math one could work out it out and find a suspiciously common term in properties?

    Kinda reminds me of when a neutron (kinda like a boson made of three quarks) is smashed producing a proton, a neutron and an itty bitty bit of energy. All together, they form a neutron again although you can find a proton and an electron and measure them... could that mean that electrons, protons and neutrons are mass particles while quarks are energy particles with the potential to become mass?

    ... hey.... whats the amount of energy created along with the proton and neutron after subtracting the energy gained by the atom to split the neutron? Has it been compared to the energy of the quarks?

    I've also gotten to the point where I believe that quarks are made of energy and not mass which explains why its so darned hard to measure them as we can only measure their change and why every time we look deeper into the atom we find even smaller bits which may end up with a mass of infinitely small. Help find a serious flaw in my logic otherwise I'm going to apply the speed of light to some of the quark equations and see what I get XD (well, I can't really so someone is gonna have to help me lol)
  16. Aug 28, 2007 #15


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    Please go easy on the speculative stuff. I strongly suggest you go over the PF Guidelines before proceeding any further. It is one thing to ask about something you don't know, or don't understand. It is another to make wild guesses. The Particle Data handbook is full of information regarding all of the properties that we know of of all the elementary particles, including the quarks. You are advised to go over them first.

  17. Aug 28, 2007 #16

    Particle handbook? I'm waiting for some books... I'll learn myself like theres no tomorrow and then come back...
  18. Aug 28, 2007 #17


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    Fullperson: Our dayly life language can not descibe quantum mechanical objects and their properties. Math seems to be the only way. And the math that describes quantum particles are quite hard.. And also, you might want to consider have taken courses is relativistic Quantum mechanics and some Elementary particle physics as final year under graduate at the university.

    And how physicists came up the formulas are kinda like their "job", to describe our nature and try to make predictions, make new models and formulas etc. And try to find applications of the new (or old) knowledge.

    Facts and Mysteries in Elementary Particle Physics by Martinus Veltman is regarded to be one of the best books that a person without any physics and so on at collage level.

    Then there is alot of books of there called "introduction to elementary particles" and so on, but a lot of them is at graduate level, so bevare ;)

    Also you can try amazon for yourself, search a bit for popular science books on QM and particles.

    Also, if you do not have noticed. An elementary particle is not a particle as a small little ball. Nor it is a wave. My teacher in advanced QM told us all yesterday {there is many people there who are physical engineers, sp they need a little refreshment;) } that an electron is an electron, noting else.

    And if you only know at what level the experiements are today, you will probably dont understand a thing :P

    For instance: The mass of the proton is much larger than the mass of its three constituent quarks, it is belived that the rest (98% or so) is created by a quark-antiquark-gluon sea..

    And was this the book you talked about ZapperZ ?
    "Handbook of Particle Physics" by M.K. Sundaresan {Iam gonna take one more course in elementary physics soon}
    Last edited: Aug 28, 2007
  19. Aug 29, 2007 #18


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    No. The Particle Data Group produces the most up-to-date list of every known elementary particles in existence, because this is what physicists in this field refers to all the time. The PDG handbook is FREE and anyone can download it. Go to


  20. Aug 29, 2007 #19
    cool, thx guys

    ps I knew that particles are not little balls its funny
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