The Bohr atom at 100


One hundred years ago, in 1913, Niels Bohr published a trilogy of papers describing the atom in ways that we are still referring to today. These papers synthesized several previous ideas into one and presented the atom as a positive nucleus encircled by a cloud of electrons that stayed in very distinct orbits that were proportional to their energy (i.e.  electrons in low orbitals were lower energy than those that inhabited higher orbitals). 

This sounds like a simple concept, but it has some very important ideas nested in it. Probably most importantly is the idea that the orbitals are distinct. That is, there is no ‘between’ orbitals. Electrons are in one orbital or another, but never in between. Also, it takes energy input to raise an electron into a higher orbital and energy is released (as light) when an electron drops into a lower orbital. As a biologist, I find…

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