What has to happen to move between shells
Most recent answer: 12/29/2019
Q:
Ane of my students asked me, "Why does the electron move at all?" I admitted I didn�t know and would like to find out for myself and for her. Thanks
- David DeCarli
Cromwell High School, CT, Us
A:
David -
Awesome question! (Give your student my compliments for thinking information technology up!) Naturally, 1 would think that because protons are positively charged, and electrons are negatively charged, the two should attract and stick together. The reason that doesn't happen can't even begin to exist explained using classical physics. This was one of the primal mysteries that were cleared up correct abroad by the invention of quantum mechanics around 1925.
The picture you often run into of electrons as small objects circumvoluted a nucleus in well defined "orbits" is actually quite wrong. As nosotros at present understand information technology, the electrons aren't actually at any one place at whatsoever time at all. Instead they exist as a sort of cloud. The cloud tin can shrink to a very minor space briefly if you lot probe information technology in the right way, but before that it really acts like a all-inclusive deject. For example, the electron in a hydrogen atom likes to occupy a spherical volume surrounding the proton. If you think of the proton equally the size of a grain of table salt, and so the electron deject would take about a x foot radius. If you lot probe, you'll probably discover the electron somewhere in that region.
The weird thing about that cloud is that its spread in space is related to the spread of possible momenta (or velocities) of the electron. So here's the key point, which we won't pretend to explain here. The more squashed in the cloud gets, the more than spread-out the range of momenta has to get. That's called Heisenberg's uncertainty principle. It could quit moving if it spread out more, but that would mean not beingness equally almost the nucleus, and having higher potential free energy. Big momenta mean big kinetic energies. So the cloud can lower its potential energy past squishing in closer to the nucleus, just when it squishes in too far its kinetic energy goes up more than than its potential free energy goes down. So it settles at a happy medium, with the lowest possible energy, and that gives the cloud and thus the atom its size.
That basically answers your question, although we admit that the answer sounds strange. In that location really are very definite mathematical descriptions to go along with those words.
You lot might be interested in some more properties of those electrons in atoms.
If just the right corporeality on energy is practical, it is possible to knock an electron up to a higher free energy orbital (a unlike shape of cloud, not then close to the nucleus), or even completely off of the atom. If electrons are knocked off of the atoms, they can create electricity. (This is what you see when you look at a VanDeGraff Generator or at lightning.)
If they are only given some energy, simply not enough to knock them loose, they will motility from 1 orbital to some other (say from the S-orbital to the P-orbital). Only if there is no other electron in the lower-energy orbital, they will fall back down again. When they do, they release energy in the class of a photon (light). This is function of the concept that lasers are based on.
Well...I apologize for this answer being so long. Thanks for sticking with me upwards to here! I hope this answers your question.
-Tamara
(published on x/22/2007)
Follow-Up #1: electrons in atom move?
Q:
How practice electrons motion around the nucleus?
- Anonymous
A:
The easiest case to describe is a hydrogen atom. It has just one electron. That electron exists in a spherically symmetric deject around the nucleus. It'south not going anywhere at all. Still, the deject has the potential to testify movement in whatever direction if something comes along to 'measure' that move. Likewise the electron can be institute in any position in that little cloud if something comes forth to measure the position to that accuracy.
If that sounds mysterious, information technology is.
Mike Due west.
(published on 06/ten/2009)
Follow-Up #ii: electron orbits
Q:
I've heard that electrons don't plummet in on the nucleus because the trajectory that they take around the nucleus must exist an integer of their wavelength, or else they will destructively interfere with themselves. Thus their wavelength, which is proportional to their energy, prevents them from collapsing, because in club to radiate free energy, the energy must exist given off at a certain charge per unit, which would cause the electron wave to destructively interfere with itself . . . My question is where do electrons get their kinetic energy, and thus their wavelengths from, and, if that wavelength theory is true, how tin they be lowered back to their orininal free energy level after being elevated by a photon, since that would cause destructive interference?
- John (age 17)
Jamestown, Ohio, United States
A:
John- Those things you lot've heard are oftentimes taught in school and pictured in popular science shows. Nonetheless they are false or as well vague to be useful.
Electrons in atoms, like all objects on a small calibration, show quantum properties which cannot be pictured in any familiar way. They don't have either a particular wavelength or a particular position.
The explanation of why the electrons don't collapse in farther toward the nucleus is more like this. In classical physics, a particle can accept whatsoever kinetic energy regardless of what position information technology'due south at, but not in quantum mechanics. The kinetic energy is determined by the shape of the same 'moving ridge-function' which also represents the likely positions of the particle. If the wave is scrunched in tightly, the kinetic energies it represents are big. So when a wave starts scrunching in close to the nucleus, its kinetic energy goes up more than its potential free energy goes down.
The ordinary diminutive size minimizes the total energy.
Mike West.
(published on 10/07/2008)
Follow-Upward #three: source of energy?
Q:
Simply THE QUESTION REMAINS, WHY DOES THE ELECTRON START Movement AT ALL? WHERE FROM DOES It GET THE Free energy?
- RAGINI (age 15)
Bombay, MAHARASHTRA, Republic of india
A:
That would exist a big problem if somehow in that location was a mode for the electrons to start with zippo energy. If an electron is floating around on its own, its kinetic free energy can be very low. However, there is then a lot of electrostatic energy associated with its electrical fields.That tin be lowered by bringing it closer to a positive accuse, like a proton. That can class a simple hydrogen cantlet. The electron will at present have more kinetic energy, but less potential free energy. The actress energy will radiate abroad as an electromagnetic field.
Mike W.
(published on 06/23/2009)
Follow-Up #4: Acceleration of charged particles
Q:
What is the property of a particle that enables particles to be accelerated by a potential difference
- Alex (age 17)
Aus
A:
It's electrical charge. A potential difference is measured in Volts. A particle with charge equal to that of an electron will experience a 1 eV increase in energy for a i V increase in potential. An alpha particle, with charge twice that of an electron, would get 2 eV increase in energy, etc. Since this quantity has an algebraic sign you can both accelerate and decelerate charged particles. By the manner, one electron volt is equal to 1.602x ten−19 joulesouth. LeeH
(published on 07/05/2009)
Follow-Upwardly #v: electron relativistic waves
Q:
what is the speed, with what the electron orbits around the cantlet, close enough to c, so relative effects apply or non ? when the electron is a lonely walker in vacuum, does it behaves like a ball or like a moving ridge( i mean is it nessesary to orbit around a nuclies, to think of it like wave-cloud-etc, while not observing ) . and if it behaves similar ball/wave, if we accelerate information technology to shut-c-velocities what would happen co-ordinate lorenzs' contraction;
- димитър (historic period 18)
българия
A:
For small atoms, relativistic effects aren't very big. The binding energy of the electron in hydrogen is virtually 13.6 eV. (That's almost -27.2 potential, +thirteen.vi kinetic.) The residue energy of an electron is about 500,000 eV. And so the kinetic energy is small compared to the residuum energy, and thus relativistic effects are small. For the inner electrons in big atoms the energies are large plenty for the relativistic effects to be major.
The basic quantum rules (the Dirac equation, for an electron) utilise whether or not the particle is in a spring state. The Dirac equation is relativistic and applies regardless of the electron'due south energy, unlike the approximate non-relativistic Schroedinger equation. The Dirac equation is still a moving ridge equation. If the electron cloud is accelerated, its spatial dimensions change co-ordinate to the aforementioned Lorentz transforms as any other spatial dimensions. If the cloud starts off spherical, it becomes pancake-shaped.
Mike W.
(published on 08/04/2009)
Follow-Up #6: non-question
Q:
I'one thousand not hither to ask a question but make a statement on this subject. Meet, the problem with Quantum Physics is that they don't take into account the universe. The universe is moving and so is the matter inside of it for 1 bones reason; we are in a black pigsty. The reason the electron is moving, because we are moving in a shape of a vortex. The most important question that most teachers and professors don't address when it comes to atoms is, why do positive charges stick together? The reply is: Gravitational Singularity. If you retrieve of earth as being an atom and people equally the electrons, the people are pulled towards the core of the earth, but due to the distance the force is weak, and we are able to motion around and keep with our daily lives. It's the same case with the atom; gravitational singularity at the core of the atom is what's property the protons together, and allowing electrons to stay in orbit.
- John (age 21)
NJ
A:
Ok, since you don't have any questions, I practise. Do you lot accept any shred of evidence for any ane of those assertions? Are yous able to calculate any bodily measurable physical quantity, like those which are calculated using quantum theory, including the attractive nuclear force?
Mike W. (published on 10/24/2009)
Follow-Up #7: why breakthrough?
Q:
Why do electrons movement like a wave? instead of a line. is there a subconscious force making them move like a wave?
- Bo (historic period 21)
NYC
A:
In almost every mod interpretation of quantum mechanics electrons (and all other small things) evidence wave-like behavior considering they are indeed waves. They are, however, quantum waves, which in some regards behave quite differently from classical waves. For example, when the moving ridge is heading toward many different-looking outcomes, yous simply meet one, not a combination. Sometimes that's reminiscent of how a particle, heading to just 1 place, would act. One interpretation, due to David Bohm, claims that these breakthrough objects are actually indicate-like coordinates influenced by a wave. So in this interpretation an electron is a moving ridge plus a coordinate dot. That'southward the closest to the picture you have in mind. Then far as I know, the Bohm interpretation adds nothing (except some hassle with relativity) to the simpler interpretation that the wave is all there is. Mike Westward.
(published on ten/24/2009)
Follow-Up #8: quantum energies
Q:
Okay, I've read the answers that have been proposed to the questions. If I get it correctly, the reason why electrons practice not collapse on the protons is because the potential and kinetic energies settle into a happy medium and thus do not send the electron pinwheeling into the nucleus. Merely one thing I would like to ask is how do the potential and kinetic energies prevent the electron from careening into the nucleus? What are the mechanics of these energies that human activity on the electron?
- Ze Xuan (age 13)
Singapore
A:
I think there's ane key ingredient here that isn't close to what one would judge based on classical mechanics. It's that the kinetic energy of the electron moving ridge depends on its shape. Specifically, it goes as the second derivative of the wave role with respect to spatial coordinates. That means that the just way to get a minor kinetic free energy is to have a wave which varies simply slowly as a function of position. Nonetheless, in order to be full-bodied in a small region (needed to lower the potential free energy) the wave obviously must vary quickly every bit a function of position. That's why at that place is a trade-off. Mike W. (published on 11/fourteen/2010)
Follow-Up #9: why quantum electron?
Q:
How is information technology that as you said in a hydrogen cantlet the electron exists in a cloud around the nucleus? Isn't information technology only 1 electron? Why is it a "cloud" around the nucleus and not like a planet effectually a star?
- Abstract1 (age 21)
detroit, mi
A:
Yes, it is just one electron. The point, withal, is that an electron is not what you call up information technology is. It actually is a smear, not a dot. That smear can, under some conditions, by pulled into a small region or under other conditions expanded out to a large region. So far as we can tell, that's all there is to it. As for the idea that there's really a dot-like position hiding in at that place, as we discuss to a higher place, violations of the Bong Inequalities evidence that such pictures are false. From the point of view of the central equations of physics, the mystery (if any) is non how an electron can be spread out only rather how the planet can be not spread out. Mike Due west. (published on 03/03/2011)
Follow-Upwardly #10: quantum facts
Q:
From the previous answers given I see no explanation for the perpetual motion of the electron? Equally far every bit I can tell Quantum Mechanics does not explain the motion of any particle? Information technology says that electrons are smears or clouds. I find this abstact mathematical explantion very unsatisfatory. I call back that the about honest answer that tin be given by a physicist is they don't really know what causes the motion of particles. Then I will rephrase the question. Why is an electron non stationary? What is the mechanical explanation for its motion? Equally of import is it really a cloud of probabilites or an bodily physical object that is impossible to mensurate in our laboratories. Since at this time in history we cannot determine the actual location and momentum of an electron why have we take settled for the pseudo explanation of a probability deject as the explantion of electron motility?
- mmfiore
Florida
A:
You're nostalgic for a world of mechanical parts. Any mechanical model- in fact, whatever model which has any local realist clarification- must obey mathematical relations called the Bell Inequalities. Unfortunately, a wide multifariousness of experiments give results flatly inconsistent with these inequalities. You may believe that relativistic quantum mechanics is a "pseudo-explanation". All the same it is spectacularly successful at predicting experimental results. For example, it predicts the electron's gyromagnetic ratio (the ratio of an electron's magnetic moment to what would exist expected in a elementary classical picture) to within ten decimal place accuracy. (come across ) There are indeed mysteries apropos the relation between the facts of the definite breakthrough beliefs of small things and the chancy behavior of large things. We can't get effectually those mysteries by pretending we don't know what we know experimentally about the small scale. Mike West. (published on 09/07/2011)
Follow-Upwards #eleven: Why exercise electrons move?
Q:
Why do atoms (or electrons) move? The thread I'thousand on has explanations of how but not why. Ragini from Bombay and mmfiore from Florida asked the same question merely I did not see an reply.
- Ray Lavey (age 65)
Bristol, RI
A:
We've been somewhat fugitive this because the reply is a bit technical. An electron exists as a wave function. The velocity of the wave part is not separate from how the wave is distributed about in infinite. In fact, the momentum is a function of how rapidly the quantum wave changes from place to place. Any electron in a confined space must have a wave function that changes from almost zero far away to something else in the central region. Since the wave office must change from place to place, the moving ridge is fabricated of components with momentum. I know this sounds pretty abstract. All I can do is recommend studying some starting time quantum mechanics. Mike W. (published on 09/18/2012)
Follow-Up #12: breakthrough hazard and determinism
Q:
As a science enthusiast, just not professional I found your statement "There are indeed mysteries apropos the relation betwixt the facts of the definite quantum behavior of modest things and the chancy behavior of large things" refreshingly surprising. From what I have been reading (admittedly a smorgasbord of books written mainly for lay readers), I had come to recall of the breakthrough world equally dicey and the classical physical world as easier to predict. Can you flesh out your descriptions a bit? Thank you
- Heather (age 44)
Us
A:
Great question. Things are usually described in the way you say, but that's left over from the confusion of early on breakthrough mechanics. I'll try to bring you up to speed with our electric current confusion. To the best of our knowledge the quantum country of anything changes following a purely deterministic (and besides linear) equation. The outset version of that, the Schroedinger equation, described the beliefs of a single particle in a stock-still classical environment. However, those basic features (determinism, linearity) have remained exact backdrop of all subsequent quantum field theories, describing many interacting breakthrough objects. Breakthrough field theories accept been confirmed endless times in an enormous multifariousness of experiments. So that leads to a large problem, often described past the Schroedinger cat story. The output state from whatever linear theory is exactly the same as the sum of the output states of the components of the input states. That means that the outcomes of typical quantum starting states include wildly dissimilar large-scale events, such as a alive cat and a dead cat, summed up or "superposed". The problem is that no one has ever seen any superposition of such different large-calibration realities. You only run into i or another, following probability rules. Somehow randomness comes in on the road from simple breakthrough rules to big-scale events. There are a diversity of means, all unpleasant, of trying to explain how this happens. They get by the name of "interpretations of quantum mechanics". Mike W. (published on ten/29/2012)
Follow-Upwardly #thirteen: electron motions
Q:
has any physicist theorized that the reason for electrons' inability to be observed for whatever 'duration' longer than an instant, is that they motion at the speed of light? and my real question is; if yous were able to run across the stream of electrons moving through a copper scroll (I don't know if you tin) would they be like a stream of water clinging to the outermost edge of the coil due to centripetal strength?
- dan (age 28)
mn
A:
To start with your terminal question, at that place is a slight trend for the electrons' momentum to cause them to concentrate toward the outside of a coil as they period through it. That effect is very small, even so, because the electric forces between them make the electron fluid nearly incompressible. The current pattern in the wire is slightly affected by the magnetic forces due to the field created by the current itself. Equally for your commencement question, electrons don't move at the speed of light. I'm not certain what y'all meant near the part about "disability to be observed". Mike W. (published on 01/09/2013)
Follow-Up #14: electron compressibility
Q:
Um, first of all, i dont know anything much about the theories you lot are talking almost....but,from what i've read, u r describing the electron as a cloud whose spread depends on the possible velocity of it. Something like, the higher the force with which a rubber-ring is stretched, the more than information technology "spreads" and disfigures from its original shape. But so in the follow up #13 u r describing it as a some sort of fluid and that it is incompressible. that is 1 thing that's confusing. the other that i dont understand is ur description of the potential and kinetic energy settling in a happy medium. i hope u dont give me some fancy named theorems or equations cz i'yard simply a 10th grader.
- Vishnu (age 15)
Chennai,TN,India
A:
Those are subtle questions. Nothing is entirely incompressible. The near-incompressibility of the electrons we mentioned above wasn't a breakthrough outcome. It'southward just that the many electrons in the metal strongly repel each other and therefore are difficult to push together. There is also a breakthrough resistance to compression, harder to explicate, that affects even single electrons. The 'happy medium' story involved that quantum springiness. Take a hydrogen atom. The positive proton in the center is pulling the electron cloud in. But the quantum springiness pushes the electron deject out. As the electron cloud gets pulled in more, both those effects grow but the quantum springiness grows more. When the cloud is merely atom-sized, the two effects balance each other. Mike W.
(published on 02/07/2013)
Follow-Up #15: breakthrough superpositions
Q:
In your answer to Q # 12: "The problem is that no 1 has ever seen any superposition of such different large-scale realities. You only see i or some other, following probability rules. Somehow randomness comes in on the route from simple quantum rules to big-scale events." I think someone has. Andew Cleland and his squad at Santa Barbara University recently (2010) demonstrated a Quantum Paddle which tin exist in ii diferent states at the same time: http://www.nature.com/news/2010/100317/total/news.2010.130.html Whatever thoughts?
- Lakhi (age 50+)
Ann Arbor, MI
A:
Superpositions of what seem similar different possibilities take been observed on increasingly large scales, including Andrew Cleland's paddles. Note that the paddle is in one state merely that land includes components with different classical backdrop, due east.g. position in this case. Interference furnishings provide the prove for the coexistence of the non-classical superpositions of different classical possibilities. It gets harder and harder to detect these superpositions on larger scales, because processes called decoherence cause loss of interference between the different possibilities. And then far we've never seen the loss of interference except when ordinary decoherence furnishings are expected. That makes us doubtable that the basic breakthrough rules apply on all scales. If so, then the superpositions would continue on all scales, just without the telltale interference effects. That would mean that our minds be in decoherent superpositions of different states seeing all the different outcomes of quantum processes. That's called the "Many Worlds" interpretation of quantum mechanics. Mike Due west. (published on 02/x/2013)
Follow-Up #16: non-classical superpositions
Q:
Thanks for your answer in Follow-up Question # 15: "Interference furnishings provide the evidence for the coexistence of the non-classical superpositions of different classical possibilities." i. How can two different classical states (positions of Cleland's paddle represent to one breakthrough state? 2. Are there some examples of these interference effects at the non-classical (breakthrough) level and how they then relate to classical possibilities? Thank you!
- Lakhi (age 50+)
Ann Arbor, MI
A:
ane. Let'southward say that state |A> represents one position of the particle and country |B> represents the other. State (0.8|A>+0.half dozen|B>) is one case of the endless quantum states that include both classical possibilities. ii. In that location are many, many such examples. Here'due south a favorite: little carbon soccerballs, buckyballs, show interference when shot through 2 slits, indicating that the land included the same buckyball simultaneously in both slits. () One might remember that some fancy theory without such weird superpositions could account for the interference effects. The many experiments which show violations of the Bong Inequalities (search this site and the web) bear witness that we really have no choice but to acknowledge that these weird superpositions are existent. Mike W. (published on 02/11/2013)
Follow-Up #17: electron moving ridge and lightning
Q:
If electrons movement in waves how come when y'all see electrons for example lightning, why does in non wait like a classic body of water wave?
- David (age 16)
NJ
A:
Hi David, Hope this helps, Lingyi
The fact that electrons are waves is somewhat counter-intuitive. as suggested past De Broglie in around 1923, electrons are waves with wavelength given by 
(published on 01/29/2013)
Follow-Upwards #18: Where is an electron?
Q:
this is a peachy post by the way...every bit for my question..from what i read i remember that when you say electrons are smears..you're talking about how we currently encounter them trough experimentation..thourgh mathematical functions....creating probabilty boundaries..because in the terminate..at that place'll have to exist something..a divers particle....it's there..as a particle..simply its too fast..as well small..too unpredictable for us to mensurate exatly..thats why we create those smears and orbital shapes and stuff...am i even partly right in this..?....and also....when you say that the elctron is spread out like a cloud..that cloud just represents different points where it could be..if nosotros are ever able to really see the electron..through any way..the actual electron..volition we find information technology continuing there..or moving around...? i'd really appreciate information technology if y'all would also throw some lite on quantum earth's reality vs. what we summate and state....i mean more than about the theory and what information technology could actually exist..and less virtually what ambiguous experiments have shown then far. Thank you
- anonymous
A:
Nice question. The answer may be simpler than yous expected. No, you are not even partly correct.
Equally nosotros discuss in diverse questions, if that picture of the electron actually being somewhere were true (and the same for other smeared quantum properties), and so some mathematical relations called the Bong Inequalities would accept to be obeyed. They are non obeyed. Therefore those backdrop (exact electron position, etc.) practice not exist. These experiments are the exact opposite of "ambiguous". They compare a definite prediction with a definite result, and find that the prediction is wrong. Therefore the ground of the prediction, the claim that those exact positions and so on exist, is imitation. It'south not just that the values change apace, or are hard to mensurate, or anything else like that. They really don't be. You ask what comes out if nosotros do a measurement which gives some much narrower range for the position of the electron. (No experiment gives an actual betoken.) We can say what happens if we do another experiment like that a fiddling later. The electron might exist anywhere over a large range. That'south just what quantum mechanics predicts, considering a narrow electron cloud has a big range of velocities. If you do the experiment many times, you discover that quantum mechanics predicts the range very precisely. Yous too ask for some more caption of quantum reality. Here we are on less certain basis, almost in the slippery realm of philosophy. I suggest having a look at these one-time answers: Mike Due west. (published on 06/30/2013)
Follow-Upwards #nineteen: why do electrons move?
Q:
I accept read all answers simply I recollect the question nevertheless remains unanswered.. why electron have to move..? according to Rutherford electrons was moving and radiating continuously.. According to Bohr electron is moving in circular orbits or you may say cloud is circular or elliptic, just my question is: Why not electron just not move in straight line toward the nucleus and plummet if really opposite charges attract.. Or reply to this is electron is falling freely just like a satellite..
- Zeeshan khan (age 22)
Islamic republic of pakistan
A:
Rutherford and Bohr did say those things just they were wrong. The entire picture underlying those descriptions is mistaken. Equally described in the other answers, electrons and all other modest objects are not classical things. The attempt to picture them every bit classical things, with definite positions and velocities, leads to fake predictions.
Fortunately, at that place's another way to describe them, mod breakthrough mechanics. In quantum mechanics both the range of positions and the range of velocities are described by the same wave function. That means that some properties of the distribution of positions are connected with properties of the distribution of velocities. That's unlike classical physics, where the position and velcoity can be described independently. One of the implications of quantum mechanics is so that a narrow range of positions is always accompanied by a large range of momenta, with a corresponding big kinetic energy. Mike Westward. (published on 08/02/2013)
Follow-Up #xx: do electrons spin around the nucleus?
Q:
I know I am playing maybe a dangerous game here, simply I'll try anyway.Simply a stupid question, naive, etc...Co-ordinate to the latest quantum mechanics: do electrons spin around the nucleus or non. Yes or no? Or is the all-time answer: we don't know?
- Promotor (age 28)
A:
By "spin" I presume y'all mean "orbit", since you specify "around the nucleus". The answer is sometimes.
In the ground states of H and He, the electrons have no orbital angular momentum and cannot be said to orbit in whatever reasonable sense of the give-and-take. In the standard states with well-divers not-zero orbital angular momentum, e.g. one of the 2P states of H, you could sort of say that the electron orbits the nucleus. That would be misleading, yet, since the distribution of positions of the electron doesn't modify in time, in sharp contrast to what you probably hateful by "spin around the nucleus". Yous tin brand states with superpositions of states of higher energy with different angular momenta that practise have lumps of moving ridge-function that do orbit around the nucleus before decaying via photon emission. Since, so far as we know, the earth is made of quantum objects and you lot practice see things in classical-like orbits, you shouldn't be surprised that something like that is at least possible for electrons in atoms. I guess I should mention one exotic possibility that would modify those answers. There's a proposed new version of quantum mechanics, not still shown to exist consistent with all the bones effects, called "Many Interacting Worlds". In that motion picture any one of the worlds does accept particles at item positions. If somehow that movie develops, is consistent with known effects, and manages to correctly predict any equally withal unknown effects, our answers will change. Mike W. (published on 03/eleven/2015)
Follow-Upwards #21: electron smears
Q:
Hi, I'1000 non even going to pretend that I understand virtually of what has been said hither, but what I am most clueless almost is the whole "smear" conversation that you were having. Every bit I know nothing of it, can you lot please explain it (in a LOT of item) for me. Too, if what I take got from this thread about electrons having superpositional qualities is truthful, how do we know that they quantum tunnel? Is it non possible that we are simply observing one electron moving into the area of the cloud of some other atom and sort of forcing another out of the other side due to (for lack of ameliorate phrase due to lack of knowledge of the subject area) being better tuned to the cantlet it is coming into contact with in a sort of newton's cradle? I know that I am incorrect, the only problem is I'm non sure why.
- Paul (age 16)
England
A:
We've discussed electron smears before (), and so perhaps information technology'due south good to starting time there then follow upwards.
On tunneling, we tin can measure rates of tunneling in a variety of circumstances. These rates are simply what is predicted by the breakthrough picture, with the tail of a wavefunction falling off post-obit the moving ridge equation. Since the same wave equation predicts the properties of atoms, the types of chemical bonds that form, etc. It wouldn't brand sense to try to put together a special classical mechanism for tunneling. Mike W. (published on 04/xi/2015)
Follow-Upwardly #22: photons equally particles
Q:
Howdy, I have been studying Richard Feynman's views on electrons and photons, and he conspicuously states that they behave every bit particles. And that the wave function does not correctly predict where particles announced. Has his view been proven incorrect since his passing? Are photons nonetheless particles in the stop?Thank you.Jeremy
- Jeremy (historic period 44)
NY
A:
Nothing much has changed in this business since Feynman wrote. Both light and electrons are quantum waves. These are different from classical waves in several ways, including:
1. You can set up counters that count individual blips, which is why we say these are "particles". 2. The blip pattern is partially random, not predictable from the wave, or from any prior local property of the universe. Mike W. (published on 05/23/2019)
Follow-Up #23: how to reach diminutive ground state
Q:
Howdy Mike W., Thanks for all your answers here. I've learned a lot reading them, fifty-fifty if well-nigh of the content is beyond my understanding. I (think I) understand from your answers (and from the Feynman Lectures, which I'one thousand slogging through) that if the electron cloud were too small-scale, its kinetic energy would be so dandy that it would overcome the strength of the electromagnetic force pulling it in to the nucleus, and the electron would "fly out" (i.e., the cloud would aggrandize) to a greater distance from where it was, and so by definition it tin can't be "at the center" where the nucleus is. This makes sense as a sort of proof by contradiction for why the electron tin't exist fatigued all the way to the nucleus (or why the cloud can't be so small so every bit to just barely envelope the nucleus), simply I however don't understand how or why the deject "chooses" where to settle. Is the cloud continually shrinking due to the electromagnetic pull and and so expanding due to its kinetic energy over very, very pocket-sized distances and at incredibly fast rates, thus appearing to sit at a item distance away from the nucleus? Or is information technology effectively the equilibrium between the electromagnetic pull and its kinetic energy? In your first answer to the original question, you say, "So it settles at a happy medium... etc." In followup #fourteen, y'all mention "quantum springiness" when explaining the "happy medium" of the size of the electron cloud in relation to the nucleus it surrounds. Would y'all listen elaborating on how it settles at a happy medium? If the quantum springiness is that elaboration, would you listen farther explaining what breakthrough springiness is? Thanks, Ilya
- Ilya Kamens (age 29)
Brooklyn, NY
A:
Corking question!
You tin can brand a listing of the stock-still-free energy states that the electron can exist in for say a hydrogen atom. We described how the lowest free energy "ground" state has a size adamant by a balance of minimizing kinetic and potential free energy. Then you enquire how the electron manages to reach that basis state, if it starts of in another state, or in some combination of other states. Those other states take more energy. You're exactly right that the electron can't end up in the ground land without ditching that extra free energy. The extra energy leaves in the grade of photons. At high temperatures there are lots of photons around, so an atom in the ground state can option up free energy and finish up in a unlike country. It's but when things are cool enough that almost all the atoms are in the ground state. Mike Westward. p.south. Historically, realizing how much kinetic energy would exist required for an electron to localize in a nucleus was a motivation for proposing the existence of neutrons, rather than just combinations of protons and electrons, to expain the different charges of nuclei with almost the same mass. (published on 12/29/2019)
Follow-Up #24: Forcing Electrons
Q:
In answering the question "Why exercise "Electrons Movement", you say "With a potent enough forcefulness, information technology is possible to give an electron plenty energy to knock it up to a college energy orbital, or even completely off of the cantlet (if the forcefulness which is giving it the free energy to motility around is stronger than the electric force holding it virtually the nucleus). If electrons are knocked off of the atoms, they create electricity" My question is, where do these forces come from? How exercise we create these forces? I'd similar to be able to explain this to my students, simply mostly I only want to know. Cheers, Sally Anne Rosenberg
- Sally Anne Rosenberg
Park School, Alhambra, Ca. USA
A:
The main forces that accelerate the electrons are (no surprise) electrical forces, from electrical fields. There are all sorts of ways of getting big electrical fields on atoms. One is to shine low-cal on the atoms, since low-cal consists of an electromagnetic wave. Another way is to combine chemicals which react (say past burning some gas). As the electrons rearrange, electromagnetic energy can be released. (published on 10/22/2007)
Once you lot get some atoms or electrons moving around quickly, say with a burner or electric heater, they tin can bounce off other atoms, transferring some of their free energy.
Follow-upwards on this reply.
Source: https://van.physics.illinois.edu/qa/listing.php?id=1195
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