Photon emission by a atom

[speeding electron]

Classically, a pulse of light emitted by an atom would be viewed as an electromagnetic wave radiating spherically symmetrically out from the atom. Quantum mechanically speaking, if say a hydrogen atom emits a single photon, does the photon's wavefunction spread out spherically, us having no idea on which side of the we will detect it? Also, am I correct in assuming that we know the magnitude of the photon's momentum exactly (p = hf/c), in which case the uncertainty in its momentum is all uncertainty about the direction of its momentum? Clarification about this situation would be great, because I haven't been able to been able to find anywhere which deals it fully.

[Tyger]

For an atom in a spherically symmetric state the amplitude for the photon to be emitted is equal in all directions. But, when the photon is actually emitted, it only goes in one direction. In Einstein's paper on the Photoelectric Effect he wrote of "needle-like radiation".

[balkan]

the momentum is h/lambda... the photon is considered a wave "package" and can be calculated as such...