In an atom, at what speed do electrons spin around in their orbitals?
544865
depends on how much an electron has been drinking
815552
It's all about quantum mechanics. Molecules can have a temporarially set speed at which they rotate, expand and contract, or move, but they can not go just a little bit slower or a little bit faster, their speeds are constant unless there is not enough energy to stay at a speed, or enough to "jump" speeds. I believe Philip Ball can describe it best:\n\nWhen a molecule absorbs light, it's energy increases- it gets "hotter," by which I mean that the molecule may shake, jiggle, or spin more vigorously. It is then said to have been "excited" by absorption. The reason why molecules absorb photons of light at some frequencies but not at others is that their motions are determined by the rules of  quantum mechanics, which place restrictions on which motions are allowed. We saw in chapter one (My note: I'm typing this straight from the book, but I can't show all of chapter one) that the electrons in atoms and molecules are not free to adopt any old orbit around the nuclei, with correspondingly arbitrary energies; instead, they are confined to a ladder of specific energy levels, with the energies in between the rungs being forbidden. The electronic energy levels are said to be quantized. In the same way, the energies of the motions that the molecules execute in space may also be quantized. The two-atom oxegyn molecule O2 for example, both rotates (tumbles end over end) and vibrates (the bond between the two atoms stretching and contracting) in free space. The energies associated with these motions may take only certain values, forming a ladder of energy levels like those for the electron energies. As the energies of rotation and vibration depend respectively on the speed of rotation (the number of revolutions per second, say) and the frequency of vibration (the number of in-and-out oscillations per second), the latter two quantities are quantized too. The o2 molecule, terefore, can vibrate only at specific frequencies and spin only at specific speeds. \n\nPhew, that was alot of typing! Yes, I did get that straight out of the book, I didn't copy-paste. He then goes on to explain how the larger an object is, the colser the energy levels are, so there is no real "forbidden zone", and therefore the object can accelerate gradually.\n\nEdit : Sorry about the typos, I'll pick them out as I find them.
220489
The question asks specifically how many electrons can the be in the third ring of an atom. So the answer is 8 not 18. There maybe a total of 18 electrons around the atom but in the third shell there are 8. This is of course using a rather outdated concept of the atom, we should not, strictly speaking think of electrons as orbiting in shells.
779218
Here's a great and simple explaination from Wikiopedia: \n\nIn atomic physics and quantum chemistry, the electron configuration is the arrangement of electrons in an atom, molecule, or other physical structure (eg, a crystal).\n\nLike other elementary particles, the electron is subject to the laws of quantum mechanics, and exhibits both particle-like and wave-like properties. Formally, the quantum state of a particular electron is defined by its wavefunction, a complex-valued function of space and time. According to the Copenhagen interpretation of quantum mechanics, a particular electron is both "nowhere at all" and "everywhere all at once" until an act of measurement causes it to be detected. The probability that the act of measurement will detect the electron at a particular point in space is proportional to the square of the absolute value of the wavefunction at that point.\n\nElectrons are able to jump from one energy level to another by emission or absorption of a quantum of energy, in the form of a photon. Because of the Pauli exclusion principle, no more than two electrons may exist in a given atomic orbital; therefore an electron may only leap to another orbital if there is a vacancy there.\n\nKnowledge of the electron configuration of different atoms helps us understand the structure of the periodic table of elements. The concept is also useful for describing the chemical bonds that hold molecules together. And in a macro sense this same idea helps explain the peculiar properties of lasers and semiconductors\n\n\nThe other links are also good sources for review and expaination\n\nGood luck
413107
I will have to answer your question in two parts.\n\nElectrons in a piece of metal move around randomly with speeds of about 10^5 m/s. This is just the thermal velocity associated with the energy the electrons possess without any electric field present.\nWhen an electric field is applied, the electrons acquire a miniscule drift velocity. This velocity is miniscule compared to both the thermal velocity AND the speed of light.\nElectrons flowing as a current have speeds no where near the speed of light, whether you speak about the thermal or drift velocities.\n\nHOWEVER, the SIGNAL DOES travel close to the speed of light. Signal speeds are typically about 2/3 the speed of light. Just do a simple coaxial cable calculation to find a wave equation, and you can find the conduction speed.\nThe reason for this is that the Electric field applied can cause electrons ALL THROUGHOUT the circuit to move, and thus the speed of the signal is greater than the drift speed of the electrons.\n\nThe other answers are wrong in saying that ELECTRONS travel close to the speed of light.\nIt is correct to say that ELECTRICAL SIGNALS travel close to the speed of light, however.
693887
Imagine you have have a source that emits pairs of electrons. Quantum Mechanics now states that one can not describe the behaviour of each electron separately, but only the pair as a whole. \nFor instance, if the spin of the first electron is pointing up, than the other must point down and vice versa.\n\nBut QM also states that the exact state of an electron (up or down) can only be known if we measure it and not before. But once we measure the spin if the first electron (say, it's up) than we know immediately the spin of the second one too, although it might be lightyears away. And if some distant observer measures that spin he will find that it is down. So somehow, the information of the fact that we performed a measurement on the first electron, has travelled to the second electron. And at a speed, faster than light.\n\nThis is the EPR paradox.\n \nBut the story is not complete yet.\nSpin must be measured relative to an axis, be it x, y or z.\nBell's equations described how a measured along one axis on the first electron is related to measurements along the two other axis performed on the second electron.\n\nSee here for a more complete explanation:\n  http://en.wikipedia.org/wiki/EPR_paradox
363174
To understand why an electron doesn't crash into the nucleus of an atom you first have to understand Heisenberg's uncertainty principle:  That it is impossible to know with absolute certainty both the location and momentum of a particle.  Any attempt to observe the location of the particle will change its momentum and vice versa.  This is the principle concept of quantum physics.  Like Einstein's description of light, this defies all logic in Newtonian physics, but it has been repeatedly proven nonetheless.  For now, just accept it.\n\nAn electron must stay a certain distance (or multiple of a certain distance) from the nucleus because it if it were within that distance we would know its location in relation to the nucleus with such certainty that its momentum would become extremely large, causing it to fly away from the nucleus.  Therefore any time we observe an atom it MUST be located a minimum distance from the nucleus which is always a multiple of Planck's constant h [6.626068x10^-34 (m^2)kg/s].
287143
From Rule 1 and 2 we are ready to obtain an expression for one of the atomic properties, in this case is the velocity of the electron. Multiply both sides of Eq.(1) by r/mv, we obtain\n\nv= Z e2/4p eo mvr\n\nbut mvr in the denominator of this equation can be replaced nh/2 pi. we immediately have an explicit expression for the allowed values of velocity of the electron,\n\nv = Z e2/2peoh n ...(3)\n\nEq. (3) tells us that the velocity of the electron is directly proportional to the nuclear charge Z (in case of hydrogen Z=1) and inversely proportional to the principle quantum number n.\n\nvn = 2.188 x 106 m/s x (Z/n)\n\nFor H, n = 1.\n\n2,188,000 m/s = 4,894,000 miles per hour\n= 0.729 %c, c = speed of light in vacuum, 3 x 10^8 m/s
505737
there are 4 quantum numbers usualy written\n(n,l,ml,ms)\n\nn = principal quantum number, it denotes the energy level of the electron - which row on the periodic table\n\nl = angular momentum quantum number, it denotes the total angular momentum of the orbit the electron is in - which group of columns on the periodic table valid values of l go from 0 to n-1. usually denoted 0=s,1=p,2=d,3=f...\n\nml = magnetic angular momentum goes from -l to l\n\nms = spin of the electron either + or - 1/2\n\nno two electrons can have all 4 quantum numbers the same in an atom by pauli's exclusion principle.\n\nthese number all come from solving schoedinger's equation for the hydrogen atom, if you understand PDE, the derivation is really cool but hard.
145018
It does not just have to do with Bohr's quantum number (n). It is also to do with the angular momentum quantum number(L) and electron spin (+1/2 or -1/2). Therefore, if n=1, L can only = 0 and the result is 2 electons. One with a spin of +1/2 and the other with a spin of -1/2. \nIf n=3, L can be either 0,1, or 2. \nMeaning, \nif n=3 and L=0 this results in 2 electrons on the sub-shell. \nIf n=3 and L=1 this results in 6 electrons on the sub-shell. \nIf n=3 and L=2 this results in 10 electrons on the sub-shell.\n\nThis results in a maximum of 10+6+2 = 18 electrons in the shell.\n\nThis is because if L=2, the maximum number of possible electron states on a sub-shell of n=3 are as follows:\n\nGiven, m = -L, -(L-1)..0..(L-1), L\n\nm(magnetic quantum number) can have a value of -2, -1, 0, 1, 2 with the electrons having a spin of +1/2 or -1/2 resulting in a maximum of 10 electons in that sub-shell.\n\nThis is all based on the Pauli Exclusion Principle which states no two fermions (electrons) can exist on the same sub-shell with the same spin and magnetic quantum number(m).
731498
The orbitals themselves have no real "shape".  The graphical representations you are looking at are actually density maps of where an electron in that orbital is most likely to be found.\n\nIf you take a look at an "f" orbital, for example, you'll see that the "shape" is not contiguous.  It looks like a hourglass going through a donut.  Electrons being the happy things they are can appear the various different permitted energy levels around a nucleus and can even "tunnel" outside the atom itself.  Just remember when you're looking at those pictures that you're not really looking at shapes but density graphs of where an electron in that type of orbital can most probably be found.
185424
It will utilise quantum mechanics. At the subatomic level, matter behaves very differently to classical mechanics that we are familiar with in everyday life. The spin property of particles is not actually the particle spinning like a top, but is a term given to their angular momentum to help explain their interaction with each other.\n\nParticles can only spin in certain allowable directions, electrons have only 2 directions, other particles can have more. The ability to be in 2 spin states at once is due to uncertainty in that the particle could be in either state until it is observed and probability functions are used to describe its state.\n\nSimilarly a particle in a quantum well (a box with walls of electric potential) will move about with its energy in a fashion that can be described by its wave function. At any measurement it will be in a certain point (although with unknown momentum) but it will vary with every measurement.\n\nThese sorts of uncertainties are what are scientists are hoping to use in quantum mechanics. Calculations will actually be performed millions of times simultaneously providing varying results, but favourable probabilities will lead to the correct answer with immeasurably small innaccurary.\n\nPotential methods will utilise the spin magnetic moments of electrons, or the position of valence (outer) or free electrons moving between pairs of ions (charged atoms) accurately positioned in a semiconductor. There is still a lot of work required.
714427
I'm sorry, but the previous answer was very misleading.  First of all, an electron's spin does not give it its charge.  After all, neutrons spin yet they have zero electrical charge.  Its spin gives it a magnetic moment, which is subtly different from a magnetic field.\n\nA charged object such as an electron moving in any trajectory will create a magnetic field.  A charge moving in a helical path will create an approximation to a solenoidal magnetic field.  In current carrying wires, the electrons are moving collinearly with the electric field created due to the potential difference, i.e. in more or less a straight line.\n\nNow, why does the moving charge create the magnetic field in the first place?  A good way to explain it is with an example.\n\nSuppose you have 2 protons (+ charge) placed close to each other, the pair initially being stationary with respect to you.  You know what would happen right?  They would drift apart, repelled by their like positive charges.\n\nNow picture yourself running very fast, past those two protons.  If you run fast enough, the relativistic time dilation will make it appear, from your perspective, that the protons are drifting apart more slowly... as if some force is holding them back.  If you consider that you running very fast with respect to the protons is the same as the protons moving very fast with respect to you, you can see that the two moving charges are having an effect on each other which cannot be explained by their electric field strength alone.  This is what we call the magnetic field, essentially a relativistic distortion of the electric field due to time dilation.
509181
H2 because it will be electronically more like Helium. It will have an electron with 1/2 spin up and 1/2 spin down. It will therefore have a happy orbital. You can also say that the bonding orbitals are occupied, and the antibonding orbitals aren't.
791911
Since you can not say exactly where an electron is at any one second,( because it is moving at the speed of light) it is better to show their location by an electron cloud with energy levels where the electrons could be expected to be.The electron density would be highest at the energy level where they were most likely to be by probability.
924334
Well, in terms of classical physics, an electron orbits the nucleus due to the electrical force.  But the theory of electromagnetism tells us that accelerating charged particles lose energy, and anything which is orbiting something is accelerating.  So, put these two facts together and the electron should lose energy and spiral into the nucleus.  This obviously doesn't happen (if it did, there would be no atoms...), so this was a serious problem for physics in the first decade or so of the 20th century.\n\nThe semi-classical explanation, created by a physicist named Bohr to solve the problems with the classical explanation, proposed that electrons could only be in orbits where the quantity called angular momentum (which is numerically the momentum of a particle times the radius of its orbit, or formulaicly pr=mvr=m(r^2)w where w is the angular velocity [think of it as the frequency of the orbit]) was some integer number times a constant (called h-bar).  This theory prevented the electron from falling into the nucleus of an atom, and it explained the Hydrogen atom perfectly.  But it didn't work for any other kind of atom.\n\nFinally, there's the quantum explanation, which emerged about ten/fifteen years or so after Bohr did his work.  In quantum theory particles are represented by probability distributions called wavefunctions (which is, depending on how you approach it, either a result of or the reason for Heisenburg's Uncertainty Principle; also, I'm playing a bit fast and loose with my terminology:  a wavefunction isn't a probability distribution, but if you basically square the wavefunction, that's the probability distribution).  Now, if you work out the wavefunction of an electron around a nucleus, it turns out to be constant in time, which means that it doesn't fall into the nucleus (or fly off into space or whatever else;  it stays around the nucleus as desribed by the wavefunction).  Of course, one thing which is interesting to note is that in many situations (incluing the simplest) the signle point (though not the radius) where the probability of finding the electron is the highest is actually in the nucleus.  :)  But if you found the electron there at one moment the next moment you could easily find it outside the nucleus.  It's random (as far as we know).\n\nNow, if this last confuses you or seems weird, well, it *is* quantum mechanics, and quantum mechanics is renowned for being very weird and confusing.  As to why you can never just find the electron always sitting in the nucleus of an atom, it basically has to do with the Uncertainty Principle.  If you knew that the electron definitely had to be in the same place as the nucleus at any given point of time, you couldn't know how fast it was moving very well at all, so a moment later the electron could be very far away from the nucleus (but not separated from it, as the electrical attraction would still be there and would keep the electron from escaping the nucleus altogether).\n\nI hope I've shed some light on this subject for you.
894776
According to quantum mechinics, an electron is not confined to an orbit as we know for satellites, it has a 'shell' of probability where it is most likely to be found. It also has the small but finite chance of being found inside the nucleus of the atom, so the anwer is 0.