How fast do electrons move when speeding around the nucleus of an atom? Don’t they move at the speed of light? And don’t electrons have weight? And according to Einsteins formula’s the closer anything comes to the speed of light…all sorts of bizarre stuff begins to happen…wieght approaching infinity is one of them.
So are their any measurable effects upon the behavior of electrons as a result of their speed in relation to the speed of light and Einstein’s formulas? Wieght? Time dilation?
Anyone have any great book or website recommendations that discuss experiments and theory relevant to my questions?
How fast is of course a somewhat nebulous question with quantum mechanics. On average, for the hydrogen atom, though, the electron moves with a velocity equal to [symbol]a[/symbol] c, where [symbol]a[/symbol] is the fine structure constant and is numerically about 1/137. (This comes from just calculating the electronic kinetic energy and setting it equal to 1/2*mv[sup]2[/sup].) In heavier atoms, the speed increases for core electrons and is probably lower than this for valence electrons.
There are definitely relativistic effects in atomic spectra. Relativity is, in fact, responsible for what’s known as “fine structure.” Included here are spin-orbit coupling and corrections due to relativistic kinetic energy, and several more. It’s also commonly stated that the reason that mercury is a room temperature liquid has to do with relativistic effects, which are supposed to be largest for that atom. Why this is I don’t really know; I don’t pay too much attention to heavy atom physics.
You can’t really think of the electron as “speeding around the nucleus.” The closest I can get to describing what the electron is doing is it’s smeared out around the nucleus, and if you look really closely at it, you might say “There it is! But I don’t know how fast it’s moving.” Or, “It’s going ac, but I have no clue where it is.” So, it’s not really going around the nucleus like a satellite goes around the earth.
Well said with the fine structure explanation, g8rguy… Of course, there’s other ways to look at a velocity too… one of which is to consider the Heisenberg Uncertainty Principle. Following through using naive estimates of the Bohr Radius, electron mass, and Planck’s constant you get a velocity greater than 110 m/sec… this is the “smearing” that’s referred to by doublips in terms of his orbitals, and as such his employment of the fine-structure “velocity” isn’t correct. Fine structure takes place on a much smaller scale (thus the higher “velocity”). It is the much smaller “velocity” that is what is “available” on a “larger scale” than Fine Structure “velocity”. (I say these with firm quotation marks because they aren’t really well-defined observables as is, say, momentum, charge, kinetic energy, angular momentum, spin, etc.) Of course, we can also get into Hyperfine splitting, Zeeman effects, and so forth, but those are all different scales and involve different considerations as was alluded to.
