orbital

Definition: 1) Quantum Mechanics and Atomic/Molecular Physics: A region in which an electron is likely to be found in an atom or molecule, determined by its total energy and its angular momentum. In the original Bohr theory of the atom, the electrons were assumed to move around the nucleus in circular orbits, but further advances in quantum mechanics complicated this view - instead the orbital came to define the region of space where there was a reasonable probability of finding the electron. Further, the shape of orbitals with high angular momentum be more complicated than simple circles or spheres. 2) Rotational Motion/Space: A hypothetical, inhabitable structure in space. Shaped like large, flat, ring, an orbital would be inhabited on its inner surface and rotated so that the centrifuge effect provided the appearance of gravity to the inhabitants and a day/night cycle was established. With the correct radius, the orbital could have both an earth length day and appear (near the edge) to have earth gravity.