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sean
01-15-2003, 06:15 PM
I asked the following question to my science teacher:

If the lowest temperature, theoretically, is when the motion of electrons around the nucleus ceases, then what happens when they are orbiting at the speed of light, meaning, according to traditional physics, the fastest they could get, and thus the hottest temperature. Does the atom split or something?

He told me that the temperature of an atom or molecule is not determined by electronic motion. I still disagree - because the motion of the atom or molecule as a whole does not make sense in causing the temperature of a substance. So can anyone answer the question of what exactly causes temperature. I'd also like to find an answer to the question I asked my science teacher.

minesweeper
01-15-2003, 06:53 PM
>>because the motion of the atom or molecule as a whole does not make sense in causing the temperature of a substance<<

Why not?

Aran
01-15-2003, 07:03 PM
i think temperature is merely the friction between your skin particles and the particles in another substance you are touching, be it the air, or ground, or whatever...

correct me if i'm wrong.

OneStiffRod
01-15-2003, 07:09 PM
can an atom HEAT UP? or does it give off heat energy?

sean
01-15-2003, 08:17 PM
OneStiffRod - Well you can absorb or give off heat energy, but I'm not ure which one "Heating up" implies - I would assume giving off heat energy since it would be hot to the touch.

Aran - Technically speaking yes. If you turn on the stove, the electrons (or particles - we're yet to resolve that issue) speed up (if this happens enough, the particles space out and become a liquid or gas, depending on the current density). When the cooler electrons/particles on your finger curiously poke that, electrons/particles collide, causing changes in temperature. The particles on the stove stop going in that direction as much, and become cooler, and the opposite happens to your finger.

Minesweeper - we'll let's talk relativity. The speed of the particle has to be in relation to something. What is it in relation to? It's aorund millions of things each day, but most objects keep roughly the same temperature for the majority of the time. There's some other paradoxes: if it is possible for an object in space to travel as close as possible to the speed of light as long as it doesn't attain that speed, then it is possible to have 2 particles travelling at 99% of the speed of light, going in opposite directions. When the 2 particles pass eachother, in relation to eachother, each is travelling at 198% of the speed of light - theoretically impossible.

I'm really not talking temperature here. The basic question is, what happens if an electron is orbiting it's nucleus at (or near) the speed of light?

Waldo2k2
01-15-2003, 08:27 PM
>>The basic question is, what happens if an electron is orbiting it's nucleus at (or near) the speed of light?

the bonds between the electrons and the rest of the atom will break. I assume it will happen at a speed much lower than that, gravity is a function of weight, the nucleus has gravity over the electrons. Speed can increase (effect) weight, soooo, theoretically the electrons will become too heavy for the nucleus to retain it's gravitational pull over them....but that leads me to wonder if that will reverse the process and make the protons and neutrons stick close to the electrons....either way it's no longer an atom in the sense that we know it.

beege31337
01-15-2003, 09:34 PM
Originally posted by Waldo2k2
>>, the nucleus has gravity over the electrons. Speed can increase (effect) weight, soooo, theoretically the electrons will become too heavy for the nucleus to retain it's gravitational pull over them....

The electrons are not held in place (only) by gravity, they are held by other forces. If it was just gravity that held them then they would just leave the little tiny weak pull of gravity towards the nucleus(very small mass) and head towards the big powerful pull of gravity of the earth(very big mass).

And in regards to the original question, temperature is the kinetic energy stored in the vibrations of molecules and doesn't have anything to do with the speed of electrons.

itld
01-15-2003, 10:13 PM
howdy,
the speed of the orbiting electron doesn't change, heat is a factor of how fast the entire molecule is moving.
changing the speed of the elctron is what fision is made of... or is it fusion??

M.R.

kevinalm
01-16-2003, 12:26 AM
Temperature at the molecular/atomic scale is a measure of speed of motion. This sounds a bit vague but it actually makes sense. If a fast moving object hits a slow moving object, odds are the fast object will slow and the slow object speed up. Relative speed of motion is what determines which direction heat is transfered, the basic definition of temperature. Of its own accord, heat energy will transfer from hot to cold. Heat energy is the kinetic energy stored in molecules/atoms.

There is a fundamental theorem in kinetic heat theory called equipartion. Simply stated, it says that energy is evenly divided between the "modes" of a molecule/atom. Posible modes include translation, rotation, vibration, etc. For technical reasons to involved to go into here, electron motion while still bound to the molecule/atom is not significant for temperature measurement. (Has to do with the low weight of an electron compared with a molecule/atom. Also, if you speed up an electron it will jump to a higher orbital, slowing in the process. At ordinary temps, electron motion is not closely tied to temperature.)

By the way, motion of all types doesn't stop at absolute zero. It's just the minimum possible motion. (Referred to as the ground state.)

As Waldo2k2 stated, at the high temperatures your talking about, molecular bonds break and atoms ionize. It's known as a plasma. At these very high temperatures, electron motion is related to temp. (The difference is that the electrons are now independent particles, and constitute equally important constituant particles of the gas.)

There is one interesting exception at ordinary temps. In electrically conducting metals, the conduction electrons are significant. This is why the best electrical conductors (aluminum, copper, silver) are also the best heat conductors.

01-16-2003, 03:33 AM
>>> changing the speed of the elctron is what fision is made of... or is it fusion??

Both fission and fusion are nuclear reactions, electrons do not play a part.

In fission, a nucleus becomes destabilised in some way and splits into two, or more components releasing energy in the process. With Uranium for example, the already unstable isotope U-235 absorbs a stray neutron which is enough to trigger the fission reaction. Fission is what drives your typical Uranium or Plutonium bombs, and nuclear power plants.

Fusion is the joinging together of two nuclei to form a larger one. The is not easy as the two nuclei have the same elctrical charge and hence repel each other. At higher energies, this repulsion can be overcome and the short range, but very poweful strong nuclear force can coallesce the two component nuclei also releasing energy in the process. Fusion is what drives the stas and your average Hydrogen bomb.

Clyde
01-16-2003, 08:58 AM
"If the lowest temperature, theoretically, is when the motion of electrons around the nucleus ceases"

That never happens, not only does that not happen, but molecules don't even stop vibrating at the lowest temperature!

Weird eh?

"then what happens when they are orbiting at the speed of light, meaning, according to traditional physics, the fastest they could get, and thus the hottest temperature."

There is no real connection between the "speed" the electrons are travelling at and the temperature.

When dealing with metals or indeed heat loss/gain via radiation then electrons are certainly involved but again "speed" is not whats important, rather the energy level of the occupied orbital.

You can have two orbitals with the same orbital angular momentum (electron "speed"), and one can have a higher energy than the other.

"He told me that the temperature of an atom or molecule is not determined by electronic motion"

He's right..... except there is no such thing as "temperature of an atom", temperature is a macroscopic property it can only be applied to macroscopic objects not individual atoms.

" I still disagree - because the motion of the atom or molecule as a whole does not make sense in causing the temperature of a substance. So can anyone answer the question of what exactly causes temperature. I'd also like to find an answer to the question I asked my science teacher."

If you place a hot object in contact with a cold object the molecules in the hot object are jiggling around faster (ie. have more kinetic energy) than those in the cold object, at the surface between the two objects there are collisions between the fast moving molecules of the hot object and the slow moving molecules of the cold object. As a result the cold object's molecules end up moving a bit faster (they gain K.E) and the hot object's molecules end up moving abit slower (they lose K.E). Ie. the hot object cools down a little and the cold object warms up a little. This process will continue untill on average both objects molecules have the same K.E. ie untill they are both at the same temperature.

Unregd
01-16-2003, 11:32 AM
If I remember correctly, an experiment was performed trying to cool some hydrogen (?) atoms to, or near, absolute zero. When the temperature of the atoms was very near to 0 K, the nuclei of the atoms condensed. At high enough temperatures, atomic nuclei break apart into their constitutuent nucleoids (protons and neutrons) and, from that, into quarks.

If this isn't completely accurate, maybe someone who has studied modern physics more can fill in the details.

alex6852
01-16-2003, 12:21 PM
By Einstein's relativety theory when the object's speed comes to speed of light(300,000 km/sec) it's mass becomes infinite. So basickly you cant go with speed of light because you'll need an infinite amount of energy to move something with infinite mass.

01-16-2003, 01:40 PM
>>> into quarks.

Into a quark/gluon plasma.

beege31337
01-16-2003, 01:48 PM
Originally posted by alex6852
By Einstein's relativety theory when the object's speed comes to speed of light(300,000 km/sec) it's mass becomes infinite. So basickly you cant go with speed of light because you'll need an infinite amount of energy to move something with infinite mass.

I'm not sure that what you are saying has anything to do with the topic of conversation, but anyway...

what you are saying may or may not ( depending on your beliefs ) apply to electrons, because, for one example, in some cases two electrons can cancel each other out. So hence if two equal size and type pieces of matter can cancel each other out and become nothing. Then according to the laws of conservation of matter, they aren't really matter and therefore don't actually have mass.

And I know someone will say, "well but electrons do have mass", which is true, but it is also true that light has mass, and it can't be argued that light isn't moving at the speed of light.

So basically Einstein probably wasn't totally correct, just closer to correct then anyone else at the time. Anyway, physics is a work in progress, so you can't assume anything considered true today, will be considered true in the future.

01-16-2003, 01:56 PM
>>> two equal size and type pieces of matter can cancel each other out and become nothing.

When a particle and an anti particle anihilate, there combined mass is converted to energy, not nothing, e=mc^2, (in it's simplest form). Matter can be thought of as frozen energy if it helps.

Clyde
01-16-2003, 04:40 PM
And I know someone will say, "well but electrons do have mass", which is true, but it is also true that light has mass, and it can't be argued that light isn't moving at the speed of light.

Electrons have rest mass, light does not.

sean
01-16-2003, 05:07 PM
Alright - I solved the problem during lunch at school. I found this paper in the library on fission, and while it is technically not fission, when electrons get close to the speed of light, the atom disintegrates, causing about as much damage and radiation as fission would. Based on this, I was able to answer my question (which is not posted here)

01-16-2003, 05:24 PM
There seem to be some inaccuracies here. First of all I don't see how you can speed up an electron. They absorb energy and go to higher energy levels, then they give off that energy (in the form of photons) and drop down to lower energy levels.

Assuming what you said is correct, that would be considered fission if the nucleus breaks apart. Fission is when the nucleus breaks apart resulting in new, more stable fragments.

beege31337
01-16-2003, 06:42 PM

When a particle and an anti particle anihilate, there combined mass is converted to energy, not nothing, e=mc^2, (in it's simplest form). Matter can be thought of as frozen energy if it helps.

I specifically said "two pieces of equal type and size matter" ( in reference to two electrons ) to make it obvious that I wasn't talking about a meeting of matter and anti-matter. I was talking about the canceling out of electrons with inverse frequencies, as seen in the common double-slit experiment. When the electrons cancel out in this fashion energy is not released.

golfinguy4
01-16-2003, 07:52 PM
Originally posted by Clyde
"well but electrons do have mass", which is true

Isn't this not known? AFAIK (which is probably wrong), they aren't really sure if electrons have mass.

Clyde
01-17-2003, 04:53 PM
" I found this paper in the library on fission, and while it is technically not fission, when electrons get close to the speed of light, the atom disintegrates"

How did they accelerate electrons in an atom/molecule to "the speed of light"?

This sounds rather odd to me

"I specifically said "two pieces of equal type and size matter" ( in reference to two electrons ) to make it obvious that I wasn't talking about a meeting of matter and anti-matter. I was talking about the canceling out of electrons with inverse frequencies, as seen in the common double-slit experiment. When the electrons cancel out in this fashion energy is not released."

The electrons do not cancel out, the probability of finding them in certain places drops to zero whilst the probability of finding them in other places rises.

For every line of destructive interference there is another of constructive interference.

"Isn't this not known? AFAIK (which is probably wrong), they aren't really sure if electrons have mass."

Well, as far as i'm aware they have mass, if i look in my Phys. Chem text book in the list of constants a value of 9.10939 * 10^-31 kg is given for the mass of an electron.

golfinguy4
01-17-2003, 10:47 PM
You're probably right. The book my school was using was quite old.