Why an electron can not be found inside the nucleus?
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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].
1112040
it is possible that an atom can support life like the earth does,  but if it does, then it would be way different and ofcource smaller. the things that make up the earth perfect to support life may be different in an electron. but it is something to think about. interesting question
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I have a partial answer for you.  In Hydrogen, the electron can be thought of as having a velocity of c/137 (the speed of light times the fine structure constant).  So it's barely relativistic.\n\nRemember that thinking of the electron as a point particle moving around a nucleus, like a planet in orbit, is not realistic.\n\nIn larger (higher Z) atoms, the electrons closest to the nucleus will have much higher "velocities" (getting closer to c).
1138753
This is a natural question if you think in terms of classical physics.  In fact, it's an even bigger problem than at first glance because, in classical physics, a charged object which accelerates will radiate energy.  So, in classical physics, all electrons would be expected to spiral in to the nucleus.  This puzzle cannot be addressed without quantum mechanics.\n\nHere's a very simple explanation.  It's not mathematically exact, but it carries the important concepts, and does give an answer fairly close to the mathematically correct one.\n\nFor simplicity, we'll consider hydrogen.  A single proton, no neutrons, and one electron.  There are no competing electrons to push each other apart, it really looks as if the best situation is for the electron to be squeezed right into the proton.\n\nRecall that in quantum mechanics, particles behave like waves.  Let's look at the electron that way.  What's the wavelength of this electron wave?  Well, we can't really say exactly, but a good approximation would be the wavelength is about the same as the width of the space in which you constrain the electron.  Put the electron in a large space, and it has a large wavelength.  Put it in a tiny space, and its wavelength is much smaller.  Ah, but remember, the shorter the wavelength, the higher the frequency, and the higher the frequency, the higher the energy.\n\nNow, you have two competing effects.  If the electron goes in very close to the proton, and stays there, then it will be lowering its electrostatic energy.  But to do that, it has to confine itself to an extremely small volume, which will give it a very high "wavelength energy".  It seems natural that there's a middle point somewhere such that if the electron got closer to the proton, its wavelength energy would increase faster than its electrostatic energy would decrease.  This sets a minimum distance for the electron from the proton.  It actually needs more energy to get closer to the proton after that.  So, the place the electron winds up is actually its lowest energy state, it's stable there, and doesn't require any injection of energy to maintain this position.\n\nAs I said, this is very non-mathematical, but it gives you an idea of what's happening in the quantum mechanics which explain the effect.
231705
Electrons are not little hard balls circling the nucleus of the atom.  They are best thought of as a cloud (a field of probability).  Think of your question as asking “why does the atmosphere not collapse to the earth?”  This is close.  See the sites below for more details:
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The assembled nucleus has less energy than the collective nucleons. If it did not\n\na) it would not hold together with the collection of + charged protons, and\n\nb) it would not require added energy in the form of colliding particles to make it come apart.
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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.
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Atom  \n\nThe smallest unit matter can be divided into whilst still retaining its chemical identity. Atoms are not single particles but complex arrangements of three types of particles. The subatomic particles, protons, neutrons and electrons, combine to form atoms. The protons and neutrons provide the bulk of an atom's mass and are concentrated into a tiny central region known as the atomic nucleus. The nucleus is held together by the strong nuclear force which acts between the constituent particles (termed nucleons ). The protons are positively charged and so mutually repel each other, but it is not until there are many of them that they overcome the nuclear force. Thus there is only one stable element beyond lead (Z=82). Whilst the radius of an atom is in the region of 10-10 metres, the atomic nucleus is about ten thousand times smaller at 10-14 metres. The volume surrounding the nucleus is where the electrons exist. They are much lighter than the protons and neutrons and carry a negative electrical charge. Being opposite in charge to the nucleus, the electrons are held in orbits around it by the force of electromagnetism. The electrons exist in electron orbitals around the nucleus. These orbitals are grouped into shells. Within each shell are energy levels which allow the electrons to exist in unique quantum states, depending upon their angular momentum (hence energy), in accordance with Pauli's exclusion principle . In a neutral atom the number of electrons equals the number of protons. When ionisation occurs, one or more electrons are provided with enough energy to escape the atom altogether. What remains is known as an ion because it is now positively charged and will behave in a different way chemically from neutral atom. The number of protons in the nucleus of an atom (the atomic number , Z) defines which chemical element it is. There are just over 110 known chemical elements and these can be arranged in a classification sequence known as the periodic table. The number of neutrons in any given atomic nucleus can also vary. The total number of protons + neutrons is termed the atomic mass number (A). Most atoms have a prefered number of neutrons at which their nuclei are stable. Atoms with more or less neutrons than the stable configuration are known as isotopes and will often undergo radioactive decay. The simplest of all atoms is hydrogen and is a special case which has a nucleus of one solitary proton and a single electron in orbit around it. It is the only nuclide (species of nucleus) with no neutron. A stable isotope of hydrogen is called deuterium which has one neutron in its nucleus; tritium is an unstable (radioactive) isotope of hydrogen and has two neutrons. See also atomic absorption , atomic emission , atomic number , molecule .
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First off, the electrons aren't located in the nucleus, only protons and neutrons.  The electrons orbit the nucleus.\n\nThe electrons in the outer shell of an atom determine it's chemical and physical properties because they determine what other elements or ions they can react with.  The relative availability of electrons in one element enables it to donate some to another element that requires them to have a full outer shell (sometimes known as the octet rule, since the first few rows on the periodic table all require eight electrons in the outer shell to be stable)  The larger the element, the more electrons (and protons and neutrons), and this gets into electrostatic attraction and repulsion in addition to electron affinity.  Electrons are also involved in crystal structure of metals and alloys, and again, how they allow crystal cells to form determines how hard or ductile a crystalline structure can be, how conductive it is to heat or electrical current, etc.\n\nOf course, the number of electrons orbiting the nucleus of an atom is only one factor affecting the physical and chemical properties.  The stability of the nucleus is another factor, which has to do with the number of protons and neutrons present as well.
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Not by bombardment with radiowaves, but bombardment with subatomic particles can remove orbital extra-nuclear electrons (there are no electrons in the nucleus), and can cause instability in the nucleus that leads in some cases to an ejection of neutrons from the nucleus or even disintegration of the nucleus.
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The K-shell electrons have a good probability of being close to the nucleus (remember that at the quantum level, particles are described by probability waves). This allows a good cross section for the interaction of the electron and a proton to produce a neutron and a neutrino.
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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.
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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.
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Orbital does not mean where an electron is.  It means it is the highest probability of where the electron exist around the nucleus.  Heisenberg said it is impossible for us to know where the electron is (since it is always moving) thus we have calculated wave functions....regions of high probably of where the electron PROBABLY is.
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It is because a a shell can occupy only a maximum of 8 electrons which satisfies the octet rule.\n\n the rules are:\nHUND's rule of maximum multiplicity\nPAULI's exclusion principle\nAUFBAU principle
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You must be one of those people who only believe in things they can tactilely handle.  The world of incredibly small objects will be a philosophical challenge, but I'm sure you're up to it.   \n\nFirst, let me give you the short and easy answer:  \n\nThe entire universe runs on a few very simple mathematical equations.  The solution of these equations is extremely difficult, but they perfectly predict and describe physical reality (when solved perfectly), so we're pretty happy with them.  \n\nMathematically speaking, orbitals and electrons exist, and because they exist and have certain properties, they must obey certain rules.  One of those rules is that only two electrons can ever fit into the same orbital, and they have to have opposite spin.  Any random orbital may have zero, one or two electrons but no more because if you tried to shove a third (or more) electron into an orbital, the orbital would vanish.  Think of it this way... its the only way that the elctrons can forever coexist without ever crashing into each other or falling apart in a chaotic state, because electrons (by Coulomb's law) HATE each other and strive to maintain maximum distance from one another while all trying to get close to the positively charged nucleus, which they LOVE.\n\nNow for the long answer:\n\nBefore you can accept that two electrons go into an orbital, you need to be able to accept that electrons exist.  JJ Thompson is credited with discovery (though not postulation of) the electron in his famous cathode ray experiments.  Electrons are evidenced regularly on a macroscopic scale through the use of electricity (the name is not coincidental!) and in such interesting objects as scanning tunneling microscopes and electron microscopes.  Robert Miliikan managed in 1901 to measure the charge on the electron in his oil-drop experiments.\n\nAn important piece of information came through Ernest Rutherford's (and his students Hans Geiger and Ernest Marsden) experiments on gold foil wherein they demonstrated that the mass of an atom resided in a small region of space in its center, which had a positive charge.  Later, Niels Bohr proposed that electrons reside in orbits around the nucleus, which would contain the protons and neutrons (both already demonstrated to exist independently).  The usefulness of Bohr's model was widely realized because it could predict experimentally observed phenomena, such as why atomic emission spectra have discrete lines while blackbody radiators give broad spectra.  \n\nA key moment in Bohr's theory was the existence of discrete energy states (that is, well-separated) that electrons could exist in.  The electrons could change energy levels, but could not occupy any energy states between those energy levels. The idea was hardly unique to Borh, having originated with Max Planck and Albert Einstein in reference to photons; yet its application to the atom was Bohr's own contribution.\n\nThis theory was pretty good, but it was a little rough.  Many very good physicists decided to work on the combination, including Paul Dirac and Erwin Schrödinger.  The final equation describing the behavior of quantum systems (and in particular atomic structure and the resultant properties) is known as the Schrödinger equation.  Solution of the Schrödinger equation provides perfect agreement with experiment (i.e. Balmer series of hydrogen) where the solution is exactly possible, and within experimental error where it is not. The Schrödinger equation is a simple, elegant, yet frighteningly hard mathematical equation relating the energy of a system to its wavefunction descriptor (remember, Einstein already showed wave-particle duality):\n<Ψ | H | Ψ > = E\n\nMax Born showed that if you multiply the wavefunction ( Ψ) from the Schrödinger equation by itself (i.e. Ψ*Ψ ) you will get a shape that corresponds to the region of space in which electrons that can exist in that level of energy (wavefunction) mo
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people have this picture in their head of what an atomic electron is like - it's a little ball and it whizzes around the nucleus really fast.  but it's not really like that.  \n\nyou have to divorce from your mind the notion that the electron has a single, fixed, localized position.  instead the electron is "spread out" over space, like a big smear in three dimensions.  a lot of chemistry teachers like to fudge this bit by saying that the electron spends "more time" in areas with higher electron-cloud density, but that's not really correct.  if it were, i could see where your confusion might come from - if it was spending some time on one side of the nucleus, it must spend some time getting back to the other side.\n\nthe truth is, in quantum mechanics an electron is "delocalized".  this means that it has no real, fixed position - instead it is spread out over a region or regions of space, and in fact those regions of space need not be connected.  the electron is quite literally in both places at once, not in one place or the other.\n\nthis is a rather small effect in atomic electrons, but if you consider a conducting metal like copper, the "free electrons" that carry electricity are extremely delocalized.  every single electron is basically spread out over the entire piece of copper.  it's kind of hard to picture, but that's why quantum mechanics is hard.\n\nhope this helps.  feel free to email if you'd like to discussit more.