# Tag Info

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In an atom, an electron can only have energies of a certain discrete set of values. These values are referred to as "energy levels". For this reason it is said that energy levels are quantizied. To go from a lower level to a higher level, a photon matching the energy difference between the energy levels is absorbed. When the electron changes energy ...

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You have to realize that all the history related in the video you linked is a short story for the long story of experiments and theories trying to fit experiments, been rejected, new theories explored until the final standard model was solidified into a physics theory. This is a very consistent model that has not been falsified by any experiments to date. ...

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Betrand Russell, in fact had mentioned this problem. Of how we would know if we have in fact reached the most fundamental level. The answer is no. We can never tell for sure. Due in part to the fact of a indivisble object has no unique characteristics or even remotely close to a special property that tells us humans im no longer divisible. Are inability to ...

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Feynman explains it best in this classic video, but here are some of the essentials. Magnets attract and repel at a distance, and there is really no way of rephrasing that fact which will explain this force in terms of "winds of force" or any similar construct and which will not incur inaccuracies and inconsistencies that will render it completely useless. ...

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No, the speed is not consistent from atom to atom. Electrons nearest the nucleus of highly charged nuclei move the fastest. In the simplistic Bohr model of a single electron atom (H, He+, Li2+...), speed is proportional to charge of the nucleus. As a consequence, relativistic effects are much more pronounced in heavy atoms.

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Quantum mechanically bound particles (like electrons in an atom or molecule) do not have well defined momentum.1 What they do have is a well defined distribution of momenta. This is one of the reasons that we say electrons are bound in "orbitals" and not in "orbits". That distribution is the same for the orbital around the same type of atom (or in the ...

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In a similar way that atoms are mostly empty space the same is true for nuclei and nucleons. The nucleus is composed of nucleons and is held together by the spill over strong forces that hold together the quarks within the nucleons ( neutrons and protons are made up of quarks and the energetic interactions between them). The reason a table top is solid is ...

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At least on current physics theories, there is nothing "solid" in the sense you mean. In most models of physics elementary particles are zero dimensional, which means, their size is a "point", whatever that means. The nucleus, in particular, is pretty "empty". It consist of soup of quarks and gluons, that is mostly energy; and both quarks and gluons have no ...

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While all these answers are fundamentally correct, especially with regards to Schrodinger and the shell model of electrons, there is one very basic means of radioactive decay, that of electron capture, which has not yet been discussed. Yes indeed, electrons orbiting around the atom can be captured into the nucleus. (For reference, see ...

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The position and orientation of a nucleus behave rather differently. In general, the position of the nucleus is at the centre of the electron cloud, essentially by definition. To get the dynamical equations that govern the atom, it is necessary to factor away the position of the centre of mass, so that the internal degrees of freedom get separated from the ...

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Mass so small that it cannot be observed, measured, tested, is unknown, but believed to exist, is not mass. it is pre-mass. It is alpha. The substance and evidence is confirmed only by our strong, unwavering belief that all things visible are made of things not visible.

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From a quantum prespective, it is helpful to categorize the energy of molecules as: electronic vibrational (bending and stretching of bonds) rotational and translational. However, these are each inclusive of potential and kinetic energy.

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The Lagrangian $\mathcal L$ and Hamiltonian $\mathcal H$ are mathematical objects that can be used to describe the behaviour of dynamical systems. In classical systems the Lagrangian is the Kenetic energy minus the potential energy, whereas the Hamiltonian is the the Kenetic energy plus the potential energy. Most systems can be fully described by the ...

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Take your lump, hit it with an x-ray or e-beam. See how it fluoresces (and absorbs, for the x-rays), http://alloytester.com/XRF-alloy-analyzers-2?gclid=CPuJzaSF27wCFYRQ7AoduSgAHg From Mg to U, hand held. http://en.wikipedia.org/wiki/Extended_X-ray_absorption_fine_structure If you want structure as well as composition, it gets complicated. If you ...

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So my question is actually twofold: how did people manage to discover them more than 100 years ago (historically), Historically there are many different ways people discovered different elements, and many ingenious ways of proving that they were actually elementary. One of the most useful and revolutionary was the discovery of Electrochemistry. Where ...

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At the atomic level, atoms have very few distinguishing characteristics. These are the result of different number and amounts of electrons, protons, neutrons, etc. as outlined in the periodic table of the elements. However, when talking about a specific element like carbon, there is no difference between a carbon particle created 4 billion years ago or one ...

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Point one : The discrete energy levels for an electron in an atom is due to boundary conditions on Schrodinger equation.Consider a particle in a one dimensional box with potential at boundaries set at infinity, and solve it! Because the potential is infinite outside the box, the wave function must be zero outside the box.The wave function must be ...

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I'm going to add to user288447's answer, with which I concur, by adding that the evidence for this comes from Thermodynamics (at least that's where I learned about it, the principle is reflected everywhere). If the identity of individual particles mattered, then the way that entropy changes when you separate a group of particles from each other would be very ...

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Does position count as a characteristic? If so, then yes, atoms do have unique characteristics. Edit: Perhaps I should rephrase this. If position counts as a characteristic, then yes, atoms do have unique characteristics.

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Fundamental particles are identical. If you have two electrons, one from the big bang and the other freshly minted from the LHC, there is no experiment you can do to determine which one is which. And if there was an experiment (even in principle) that could distinguish the electrons then they would actually behave differently. Electrons tend to the lowest ...

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