# I have heard there is only one component of the atom momentum quantized, (Lx, Ly, Lz) then, does it have an orientation in space?

Asked by: Roberto### Answer

Yes, the angular momentum of an electron in an atom has a quantized orientation in space, though it cannot be determined exactly. Angular momentum is a vector quantity, meaning it has both magnitude and direction, and can be described by three components (in three dimensions).As a consequence of the Heisenberg uncertainty principle, once we determine the magnitude, only one component can be determined at any time, because determining a second would give enough information to deduce the third and violate the principle that we cannot simultaneously determine the position and momentum of a particle. One way to picture our understanding of the angular momentum vector is as an arrow with a fixed length (magnitude) that makes a fixed angle from the horizontal, but that can rotate freely about the vertical, tracing out the shape of a cone. The one determined component (by convention Lz) is itself quantized, which corresponds to different specific angles from the horizontal, which therefore trace differently shaped cones, representing different quantized sets of spatial orientations.

Answered by: Edward Faulkner, Physics Undergrad, West Point, NY

'I beseech you to take interest in these sacred domains so expressively called laboratories. Ask that there be more and that they be adorned for these are the temples of the future, wealth and well-being. It is here that humanity will grow, strengthen and improve. Here, humanity will learn to read progress and individual harmony in the works of nature, while humanity's own works are all too often those of barbarism, fanaticism and destruction.'

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**Louis Pasteur**(

*1822-1895*)