<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Okay easy High-school question. So why do electrons not just spiral down into protons in the nucleus?You tell me? Also why do Nuetrons have such a strong grip on protons? Could they be eletrically attracted? <br />Posted by why06</DIV></p><p> That is an excellent question. It is in fact one of the key questions that led to the developmente of quantum mechanics.</p><p>The modern explanation is a bit more complicated, but the original explanation gets the point across. Let us consider the hydrogen atom, one proton and one electron.</p><p>You can reasonably imagine a particle like an electron with an negative charge orbiting a positively charged proton in exactly the same way that a satellite orbits the earth, both the electrostatic attraction and the gravitational attraction being inverse square laws. But an accelerating charged particle (and circular motion with a constant change in direction is an accelerating motion) must radiate energy in accordance with Maxwell's equations. So an electron orbiting a nucleus would be radiating energy, slowing and ought therefore to spiral into the nucleus. But it doesn't and this was a puzzle.</p><p>But quantum theory came to the rescue to provide an explanation. de Broglie postulated that all moving objects, like the electron orbiting the nucleus have an associated wavelength</p><p>The first de Broglie equation relates the wavelength <span class="texhtml">λ</span> to the particle momentum <img class="tex" src="http://upload.wikimedia.org/math/2/6/7/2675094f0e669eb219507d5a069943e4.png" alt="~p~" /> as</p><dl><dd><img class="tex" src="http://upload.wikimedia.org/math/b/a/4/ba4a990908bb476038b7e8cabe3a0a9c.png" alt="lambda = frac{h}{p} = frac {h}{gamma mv} = frac {h}{mv} sqrt{1 - frac{v^2}{c^2}}" /> </dd></dl><p>Bohr proposed that an electron orbiting a nucleus could only have an orbit in which the circumference was an integral number of wavelengths. This implies that there are only discrete energies that are allowable for the electron orbiting the nucleus, and therefore it cannot continually radiate energy away. This theory accurately predicts the emission spectra for hydrogen and provides an explanation for why the atom is stable.</p><p>The explanation for nuclear forces is a LOT more complicated and involves the strong and weak forces and wha tis called quantum chromodynamics. </p> <div class="Discussion_UserSignature"> </div>