(which can have the value 1 or 2 or 3, etc.) which is required to specify each of the particle's possible energy eigenfunctions (spatial wavefunctions). [P11.2]
for: a confined particle
is: a quantity whose possible values characterize the possible eigenfunctions (wavefunctions) of the particle. [P8.3]
is exemplified: for a particle confined in one dimension between parallel plates, by the one quantum number (which can have the value 1 or 2 or 3, etc.) which is required to specify each of the particle's possible energy eigenfunctions (spatial wavefunctions). [P11.2]
is exemplified: for a particle that is confined in three dimensions in a cube, by the three quantum numbers 
can each be equal to 1 or 2 or 3, etc.) which are required to specify each of the particle's possible energy eigenfunctions (spatial wavefunctions). [P11.2]
most usually is: a number (or one of a set of such numbers) specifying a particular energy eigenfunction (spatial wavefunction) and the corresponding energy eigenvalue (energy level) of the confined particle. [P10.3, P10.4]
is exemplified: for electrons in an atom, by the principal quantum number the orbital angular momentum quantum number 
the orbital magnetic quantum number 
and the spin magnetic quantum number 
[P8.3, P11.3]
Copyright 1997, The Open University