I kno it has something to do with Pauli's exclusion principle and quantam numbers.
128340
For the nth level, the quantum numbers left are l,m, and s.\nWe have that l goes from 0 to n-1 and is an integer, and m goes from -l to l and is an integer, while s takes on two values +-(1/2). Pauli's exclusion principle says that no two electrons can have exactly the same quantum numbers. So there is one electron for each valid choice of l,m, and s. Now count the possibilities.
165727
The quantum number description of an electron *is* the electron, in a sense, so two electrons with the same quantum numbers would be the same electron.
519000
Mg has 12 electrons\nwe will fill them from lower orbitals to higher\none orbital needs 2 electrons to fill in\n1s : one orbital, 12 electrons: 2e\n2s : one orbital, 10 electrons : 2e\n2p : three orbitals, 8 electrons : 6e\n3s : one orbitals, 2 electrons : 2e\n\nSeveral rules govern the placement of electrons in orbitals (electron configuration). The first dictates that no two electrons in an atom may have the same set of values of quantum numbers (this is the Pauli exclusion principle). These quantum numbers include the three that define orbitals, as well as (the hitherto unmentioned) s. Thus, two electrons may occupy a single orbital, so long as they have different values of s. However, only two electrons, because of their spin, can be associated with each orbital.\n\nAdditionally, an electron always tries to occupy the lowest possible energy state. It is possible for it to occupy any orbital so long as it does not violate the Pauli exclusion principle, but if lower-energy orbitals are available, this condition is unstable. The electron will eventually lose energy (by releasing a photon) and drop into the lower orbital. Thus, electrons fill orbitals in the order specified by the energy sequence given above.\n\nSo you will have to fill the electrons that have the same spin\nevery two electrons of an orbital have different spin but two electrons of two orbital can have the same spin\n\nyou can use a rectangle to represent for an orbital, an arrow to stand for an electron,( up or down is the spin of that electron )\ngood luck
64928
Apparently it is an attempt (a rather odd one in my opinion) to model the nucleus of the atom without the use of the strong and weak nuclear forces, which every particle physicist I'm familiar with (and that's a lot; I used to teach physics for a living) accepts as standard.
182938
This is a macroscopic analogy of quantum tunnelling, whereby a particle has a non-zero probability of overcoming a potential energy well. See the source for more details.
105946
Sounds like you're asking about a quantum mechanical phenomenon sometimes called "spooky action at a distance."\n\nIn it's most basic form, it involves two "entangled" electrons (or any subatomic particle) If you could separate the pair by some great distance--even light years--and then influence some characteristic of one electron, its distant twin would react instantly to assume the same characteristic.\n\nTry this website for a more complete explanation -->http://www.everything2.com/index.pl?node_id=138524
354428
It means that electrons have both particle-like and wave-like behaviour (for example they demonstrate interference).\n\nwavelength = planck's constant/(mass x velocity)
643525
OK.  There was a discrepancy in the atomic mass of elements.  We have electrons, which have insignificant mass, and an equal number of protons (to make the atom neutral), but the atomic mass exceeds the sum of the masses of the protons + electrons.  So we hypothesize that there is another particle in the atom which has atomic mass roughly the same as a proton but no charge.\nIt makes sense that this particle is in the nucleus.\nBUT, we can't use magnetic properties to isolate this particle.  And an atom is pretty much indivisible.  So we must actually strip off the electrons AND the protons to isolate neutrons.  That's not easy.
519343
Firstly. it's not squared (even it says 2 on the top). It says how many electrons u got on that 1S sub shell and on 2P sub shell. Carbon has 6 electrons and these electrons filled in to sub shells according to Pauli's exclusion principle. 2 electrons filled into 1S sub shell, another 2 electrons to 2S sub shell and rest 2 electrons filled into 2P sub shell. Remember that (S) sub shells hold on 2 electrons and P sub shells can hold 6 electrons. But in this case after 4 electrons are filled into S sub shells and the balance is 2 electrons. So it can be filled into P. If there are electrons more than 6, for ex 10.. 2 goes into 1S, another 2 goes into 2S and rest 6 electrons fill into 2P. This is how it happens
321706
Just goanna tell you why it is like that physically not mathematically but the math part I think you already know.\n\nFor starters there aren't any 2 level lasers there are 3 level lasers and 4 level lasers (4 levels is better then 3) never 2, you will understand why.\nNow first of all you have three processes:\nStimulated emission ;(SE)\nStimulated absorption ;(SA)\nSpontaneous emission;\nThe first two are absolutely symmetric they work with the same constants, they have just one difference, the SE is   proportional to the number of electrons in the exited state and SA proportional to the number of electrons in the fundamental (I do not consider empty places because in practice they aren't really important, don't know if you have saw them if not forget it). Now imagine your gain medium in the fundamental state, you pump it, the medium passes to have more electrons in the exited state, you pump it hard, so now what happens you have the 3 processes. The SA increases the population in the upper level and the SE in the lower level, the SA at first is more successful because there are more atoms in the fundamental state. But you arrive to a point where the population in the 2 levels is equal then both processes have the same intensity, that’s the limit of this system equal population, but you pump even stronger  trying to get an inversion population, what happens? Both process are equal in intensity the population will not vary, now let’s consider the third process. This is a less intense process if you pump well; this will just contribute to the population in the lower level, so you never arrive to have half the atoms in the upper state because even if the SA and SE are equal the spontaneous emission will create one more atom in the lower level.\n\nYou can never have population inversion in a 2 level system. There aren't any lasers with 2 levels, but you can do the calculations for. If you do not understand why population inversion is important here it goes:   you always have lost in your cavity, reflection in the gain medium, output coupler ...Only when you built a laser you see: there are "huge" losses in the laser everywhere. So you have to compensate that with a gain at every passage, well your gain medium only will have a gain > then 1 if you have population inversion, if not your medium will absorb and emit the same quantity having given 0 photons in plus to your system, So you will lose photons at every turn your light will end up really quickly.\n\nNow 3 level systems, in this systems you can pump really hard to the level 3 you can pump electrically by other means, you can pump it optically… but for instance imagine that the only thing getting out of 3 is the spontaneous decay from 3 to 2 only (which is possible, stimulated emission from 3 to 1 might not even be possible) then you can have more atoms in 2 then 1 you have population inversion. 3 level systems are the ruby, first laser ever built, and the Nd:Yag a very powerfull laser, used a lot \n\nIn relation to 4 levels 3 levels systems difference, there you can see the following, when you start to pump in the 4 level systems your base state (in relation to the emission line), is desert you have population inversion immediately, is easier to obtain gain.\n\nTo finalise this part of the answer I can tell you that getting energy out of a 2 level system would be like getting more energy then the one you input it would violate the thermodynamic law the energy conservation principle.\n\nThe second part of the question, I do not now if you where talking in the 2 level or in the 3 level system but I suppose it’s the 3 level system all the way.\nNow the answer to your question is one of most beautiful things that the basic laser physic has, remember you have medium and a cavity, this cavity reproduces it self times and times over. You need the source in 1 to 3 and you create population inversion, now your medium will emit in all directions b
165403
I see it this way, when and atom it's close to get his 8 covalent electrons, it' easy for it to attract more electrons (It needs less!), that's why the last column it's practically inactive, their outer atoms are fulfilled already
510524
Four.\n\nThe first one is usually called "n" and it gives what people think of when they say "energy level".  It's also called the "principal quantum number", I think.\n\nThe next one is usually called "l" (el) and for a given energy level, it can be anything from 0 up to "n-1".  These correspond to what people sometimes call "shells", such as the s, p, d, f, etc. shell.\n\nThe next one is called "m" and is sometimes called the "sub-shell".  Each shell can have up to "2*l+1" sub-shells.  So an "s shell" (l=0) can have 1 sub-shell.  A "p shell" (l=1) can have 2*1+1=3 sub-shells, etc.\n\nThe final quantum number is called "s" or "spin".  For each sub-shell, this can take on one of two values, +1/2 or -1/2  in some books.  This means that only two electrons are allowed in any given sub-shell.\n\nSo for n=1, the only option is l = 0, which means further that m must be 1, with 2 choices for s.  This all means that the first energy level can only hold 2 electrons.\n\nFor n=2, l can be either 0 or 1.  For l =0, m must again be 1, allowing 2 electrons.  For l = 1, m can be as much as 3, each allowed to have 2 electrons.  So adding the 2 electrons for the l=0 subshell to the 6 allowed in the 3 possible subshells for l=1 (6 electrons we get a total of 8 electrons allowed in the second energy level.\n\nYou can continue on to get totals of 18 (2 + 6 + 10) for the 3rd energy level (n=3; l =0, 1, or 2;  and m = 1, 3 and 5, each with 2 electrons allowed).\n\nThis is where the numbers that correspond to "filled energy levels" come from in the periodic table.
556783
Sure, it makes logical sense as an idea. But how helpful are these categories in reasoning? I dont imagine that they would be very helpful at all since it is very unlikely to ever find two things that are exactly alike. They might look alike but dont forget about the very subatomic particles which comprise them. Just food for thought.
16545
Quantum mechanics is a mathematical theory that can describe the behavior of objects that are roughly 10,000,000,000 times smaller than a typical human being. Quantum particles move from one point to another as if they are waves. However, at a detector they always appear as discrete lumps of matter. There is no counterpart to this behavior in the world that we perceive with our own senses. One cannot rely on every-day experience to form some kind of "intuition" of how these objects move. The intuition or "understanding" formed by the study of basic elements of quantum mechanics is essential to grasp the behavior of more complicated quantum systems. \n\n\nPlease visit the below url for moe information
164639
Causality itself is a problem in QM. What QM does is give the probability density of these virtual particles and the adjustments to other calculations that must be made to take them into account. It also gives the probabilities of actually measuring certain particles when you do specific experiments. It does not talk about cause or effect for actual observations, though. Just probabilities.
107661
Better than what?\n\n\nHere's a description of the result:\n\nEach successive "shell" has the capacity to store one more group of paired electrons in a new kind of orbital.\n\nPrincipal quantum number 1:\n1 s-orbital\n- will hold one pair.\n\nPrincipal quantum number 2: \n1 s-orbital\n- will hold one pair.\n3 p-orbitals\n- will hold 3 pairs.\n\nPrincipal quantum number 3: \n1 s-orbital\n- will hold one pair.\n3 p-orbitals\n- will hold 3 pairs.\n5 d-orbitals\n- can hold 5 pairs, but due to "crowding" wait until the 4th S orbital is filled. Are available to help form double bonds for elements like P, S and Cl though.\n\nFor principal quantum number 4 there is the addition of 7 f-orbitals, which insert themselves after the first d-orbital of the next higher principal quantum number is filled.\n\nAs a result, there are lots of rare metals which form 3+ ions...\n\n\nNow why is this so?\n\nThere is no easy way to explain this with classical mechanic and electrostatic. It has to do with standing waves, elimination by interference, and the wave/matter duality. In short, quantum mechanics. If you don't want to start with that topic, just accept that this is how it works...
412358
The Heisenberg uncertainty principle (developed in an essay published in 1927) provides a quantitative relationship between the uncertainties of the hypothetical infinitely precise measurements of p and x as measured by the sizes of their distributions in the following way: If the particle state is such that the first measurement yields a dispersion of values Δx, then the second measurement will have a distribution of values whose dispersion Δp is at least inversely proportional to Δx. For the limiting case, the constant of proportionality is derivable using commutator arithmetic. It is equal to Planck's constant divided by 4π.\n     This stipulates that the product of the uncertainties in position and momentum is equal to or greater than about 10−35 joule-seconds. Therefore, the product of the uncertainties only becomes significant for regimes where the uncertainty in position or momentum measurements is small. Thus, the uncertainty principle governs the observable nature of atoms and subatomic particles while its effect on measurements in the macroscopic world is negligible and can be usually ignored.\n     The Heisenberg uncertainty relations are a theoretical bound over all measurements. They hold for so-called ideal measurements, sometimes called von Neumann measurements. They hold even more so for non-ideal or Landau measurements.