Atoms

[hell7fire1]

So,we know that atoms have a nucleus with positive particles protons and neutral particles neutrons
and we have negative particles electrons in orbit around the thing

When scientists first had this thought,they had to very simple questions,
one stupid and easy
the second mindbogglingly difficult

if i tell you the questions,you will probably wonder why any ordinary person didn't ask the same question everyday

heres some stuff to search about

1.If electrons are negative and protons positive,what keeps the electrons from going straight into the nucleus and collapsing the whole thing?
2.If protons are positively charged,What in the world keeps so many particles with such great amounts of the same charge from repelling each other?I mean,if you have 2 north poles 10m away it takes x force to keep them there, it takes 2x force to bring them 5m away,4x force to bring them 2.5m......how much force would it take to squash them 1 trillionth of a cm together

discuss

[kimham8a]

uhh i learned this in gr 9, if my memory serves me well, question 1 is the centrifugal force equally countering the gravity and magnetic forces

Q2 is because of two reasons. One, the neutrons in between multi-proton atoms help lessen this force. Two, the fourth and most powerful of forces, the strong force (no kidding here), which acts similarly to gravity but only in close distances and much, much stronger, keeps those positive sub-particles together.

So, was I right? I think so, might have missed a few details.

[hell7fire1]

1. was the easy one,its just like when you swing a weight tied with string to your hand around, its movement(i'm not sure whether I would be right to use the word momentum) will keep it in orbit around your hand even though gravity will be pulling it downwards,it won't get closer and it wont swing of as long as the string holds

Q2 is not totally correct,you left out one main thing,
Technically holding together two people who absolutely hate each other and would do just about anything to sprint in completely different directions qualifies as work.
Work takes energy.

And they actually did name it the strong force,because it really is strong

[Bloodshadow]

No. The answer to #1 is not centrifugal force, because electrons don't revolve around atomic nuclei. Quantum effects keep electrons from collapsing into the nuclei. Electrons are waves, so when confined around the the nuclei they form standing waves; only certain discrete energy values are allowed for these standing waves, and collapsing into the nuclei is not one of these allowed states. You need to understand a bit more about quantum mechanics to explain why this is the case. In fact, this question is one of the signs that classical physics is not quite enough to describe small-scale phenomena.

Note that what I explained above only applies for electrons confined around nuclei. If you just shoot a free electron at a completely exposed nucleus, you can still get them to collide.

Technically holding together two people who absolutely hate each other and would do just about anything to sprint in completely different directions qualifies as work.
Work takes energy.

No, that is not correct. Work is not required to keep protons and neutrons together. In fact, because of the strong nuclear force, protons and neutrons bound together have lower energies than if they were separate, which is why they stay together at all. The attraction of the strong force is far greater than the repulsion of the electromagnetic force.

[kimham8a]

No. The answer to #1 is not centrifugal force, because electrons don't revolve around atomic nuclei. Quantum effects keep electrons from collapsing into the nuclei. Electrons are waves, so when confined around the the nuclei they form standing waves; only certain discrete energy values are allowed for these standing waves, and collapsing into the nuclei is not one of these allowed states. You need to understand a bit more about quantum mechanics to explain why this is the case. In fact, this question is one of the signs that classical physics is not quite enough to describe small-scale phenomena.

Note that what I explained above only applies for electrons confined around nuclei. If you just shoot a free electron at a completely exposed nucleus, you can still get them to collide.

Technically holding together two people who absolutely hate each other and would do just about anything to sprint in completely different directions qualifies as work.
Work takes energy.

No, that is not correct. Work is not required to keep protons and neutrons together. In fact, because of the strong nuclear force, protons and neutrons bound together have lower energies than if they were separate, which is why they stay together at all. The attraction of the strong force is far greater than the repulsion of the electromagnetic force.

  Are you a physicist?

P.S.
Next time please speak in English, I don't understand the explanation of question 1. 

[Aves]

Explanation of question 1: Technically, electrons are crashing into the nucleus all the time. The probability that the electron and the nucleus occupy the same space certainly exists. If you remember Heisenberg's uncertainty principle, we can only calculate the relative location and momentum of the electrons at any instant. Thus the location of the electron is, according to theory, a probability that it will be in a certain position at a certain time. As far as we can say, the electron occupies all positions in its' probability wave simultaneously until an outside force (our observation) changes that.

Explanation of question 2: I believe that's the entirety of how we came up with the Strong Nuclear Force. It was concluded/calculated to fit the observations of experiments. The four fundamental forces are theories- theories with heaps and heaps of evidence, and theories that keep improving and getting updated, but still theories. 

[kimham8a]

Explanation of question 1: Technically, electrons are crashing into the nucleus all the time. The probability that the electron and the nucleus occupy the same space certainly exists. If you remember Heisenberg's uncertainty principle, we can only calculate the relative location and momentum of the electrons at any instant. Thus the location of the electron is, according to theory, a probability that it will be in a certain position at a certain time. As far as we can say, the electron occupies all positions in its' probability wave simultaneously until an outside force (our observation) changes that.

Explanation of question 2: I believe that's the entirety of how we came up with the Strong Nuclear Force. It was concluded/calculated to fit the observations of experiments. The four fundamental forces are theories- theories with heaps and heaps of evidence, and theories that keep improving and getting updated, but still theories.

How can anything occupy multiple places at the same time? Sounds like science-fiction (don't worry I still believe you).
Can it currently be explained well?

[Aves]

If you can understand the wikipedia article, here: http://en.wikipedia.org/wiki/Uncertainty_principle

Otherwise...
Mmm... not sure how to explain it too well. Here goes;

Science is all about measuring things. We measure things and come up with theories to explain them.
Physics is the study of matter and energy, where we study what makes up stuff.
Classical physics is a model in physics- it's a set of theories and laws that are reasonably accurate in explaining things. Here, we see stuff like the atom and the electron.
Quantum physics is a group of theories trying to explain everything that classical physics can't.

Classical physics doesn't work on really small stuff- our observation has limits. At a certain point, we can't be sure of everything- we can only be sure of one thing or another thing, but not of both. It's a bit more complicated than that, but we can ignore that for now. That's basically uncertainty principle.
Quantum physics is basically everything not in classical physics- it tries to explain stuff that classical models can't.
The uncertainty principle is part of quantum mechanics.

In the case of the electron, uncertainty principle means that we can't see all the properties of electrons. We have an uncertain relationship between an electron's momentum and its position. In other words, we can only know with certainty one property, and the other one has to be described by a probability. In the case of position, that probability spreads itself out through space, becoming infinitely small as it goes infinitely further away from the nucleus.

[Bloodshadow]

Are you a physicist?

Undergraduate physics major.

Wikipedia is generally not very good source if you're looking for information in a subject you're not familiar with. Its articles usually use a lot of jargon, which require knowledge in the subject to understand, knowledge that you don't have. A better bet is just to google "introduction to [whatever subject]" or something.

How can anything occupy multiple places at the same time? Sounds like science-fiction (don't worry I still believe you).

You might know that light behaves both like a particle (photons) and a wave (electromagnetic waves) when measured in different ways. In fact, as far as we know, all particles behave like waves too, including electrons, at small enough scales. The "electron wave", in addition to exhibiting wave-like behaviors (diffraction, interference, etc.), also turns out to describe the probabilities of finding the electron as a particle, in regions of space occupied by the wave. Well, not exactly, but the mathematical details are not really relevant to this discussion. Since, as a wave, we don't really know where the electron is until we measure it (like Schrodinger's cat), we just say that the electron is in all those places at the same time until we measure it.

Anyways, the important part is that electrons don't revolve around the nucleus like planets revolve around stars. They exist as stationary wave patterns around the nucleus. Because they're waves, there are only certain shapes they can take on, and "sucked into the nucleus" is not one of those allowed shapes; otherwise the aforementioned uncertainty principle is violated. Thus, the electrons can't be sucked into the nucleus.

If you're wondering why the centrifugal force explanation doesn't work, it's because if that's how it works, the electrons would emit electromagnetic waves as they spin around the nucleus. They would lose energy this way, which would cause their orbits to become smaller and smaller, until they crash into the nucleus. If this is how it worked, all atoms would self-destruct in a few milliseconds or something, and glow brightly at the same time.

Note: The "electron waves" I said above are not the same thing as electromagnetic waves. Electromagnetic waves are light waves, made of photons. "Electron waves" are made of actual electrons. They're very different kinds of particles.

[AnonymousRevival]

Well, I hope this isn't too much of necroing a thread but.....

For Q1, According to my research because the fact that the electrons have to be in discrete energies, causes the electrons to stay in orbit around the nucleus.
Also, because the angular velocity of an electron (which can be calculated through mvr, where m is mass, v is velocity, and r is the radius of the electron orbital) is proportional to the distance between the electron and the nucleus, which is why the electrons do not lost energy and end up spiraling to the nucleus.

As for Q2, The reasons why atoms stay close intact together (If I understaood your question correctly) is because of the strong force, one of the four fundamental forces of the universe. The force carrier particle is called a "gluon" and what it does is that it literally glues the protons together from repelling each other apart, by changing the "colour" of the quarks in the protons. However, the strong force only operates in very miniscule distances. This is why heavy nuclei like uranium are radioactive, because the uranium nuclei is too large for the strong force to fully operate, and so they decay.

[Annele]

If you can understand the wikipedia article, here: http://en.wikipedia.org/wiki/Uncertainty_principle

Otherwise...
Mmm... not sure how to explain it too well. Here goes;

Science is all about measuring things. We measure things and come up with theories to explain them.
Physics is the study of matter and energy, where we study what makes up stuff.
Classical physics is a model in physics- it's a set of theories and laws that are reasonably accurate in explaining things. Here, we see stuff like the atom and the electron.
Quantum physics is a group of theories trying to explain everything that classical physics can't.

Classical physics doesn't work on really small stuff- our observation has limits. At a certain point, we can't be sure of everything- we can only be sure of one thing or another thing, but not of both. It's a bit more complicated than that, but we can ignore that for now. That's basically uncertainty principle.
Quantum physics is basically everything not in classical physics- it tries to explain stuff that classical models can't.
The uncertainty principle is part of quantum mechanics.

In the case of the electron, uncertainty principle means that we can't see all the properties of electrons. We have an uncertain relationship between an electron's momentum and its position. In other words, we can only know with certainty one property, and the other one has to be described by a probability. In the case of position, that probability spreads itself out through space, becoming infinitely small as it goes infinitely further away from the nucleus.

Is it also something to do with the fact by measuring, we determine how big it is?

^ I heard that somewhere and am keen to find out more.

[AnonymousRevival]

There are three major disciplines in physics: classical, quantum and relativistic (this would not be introduced since relativistic physics has nothing to do with this topic exactly)

Classical physics is the physics that we understand. It is logical, makes sense and it can be explained mathematically, and with the right measurments, 100% of the answers will be correct (excluding negligible uncertainties of course)

Quantum physics is more about probability. It explains why subatomic entities can undergo through particle-wave daulity or even teleportation.

To answer your question, Annele, if I understood it correctly, through measuring in terms of classical physics, we can be really accurate, but quantum physics is a whole other story. We can't for example, know exactly for sure what the mass, velocity or size of what the electrons or protons are. This is because they are subatomic entities, and they do REALLY WEIRD ILLOGICAL STUFF like .

If you want to know more about why we can't exactly measure the exact mass, size or velocity of an electron. Don't hesitate to reply, or feel free to send me a message.