Unformatted text preview: 33. (a) All states with principal quantum number n = 1 are ﬁlled. The next lowest states have n = 2. The
orbital quantum number can have the values = 0 or 1 and of these, the = 0 states have the
lowest energy. The magnetic quantum number must be m = 0 since this is the only possibility if
= 0. The spin quantum number can have either of the values ms = − 1 or + 1 . Since there is
2
2
no external magnetic ﬁeld, the energies of these two states are the same. Therefore, in the ground
state, the quantum numbers of the third electron are either n = 2, = 0, m = 0, ms = − 1 or
2
n = 2, = 0, m = 0, ms = + 1 .
2
(b) The next lowest state in energy is an n = 2, = 1 state. All n = 3 states are higher in energy. The
magnetic quantum number can be m = −1, 0, or +1; the spin quantum number can be ms = − 1
2
or + 1 . If both external and internal magnetic ﬁelds can be neglected, all these states have the same
2
energy. ...
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This note was uploaded on 11/12/2011 for the course PHYS 2001 taught by Professor Sprunger during the Fall '08 term at LSU.
 Fall '08
 SPRUNGER
 Physics, Energy

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