PHYSICAL AND CHEMTCAL PROPERTIES OF THE ELEMENTS 97
to the $ terms—in contrast to those corresponding to the P and
D terms—penetrates partly into the region of the orbits of the
inner electrons during the course of its revolution. These investi-
gations contain without doubt important hints, but in reality the
conditions must be very different for the different alkali spectra.
Instead of a 2t orbit as in lithium we must thus assume for
the spectrum of sodium not only that the first spectral term in
the S series corresponds to a ^ orbit, but also, as a more detailed
consideration shows, that the first term in the P series corresponds
not to a 2a orbit as indicated in fig. 2, but to a 32 orbit If the
numbers in this figure were correct, it would require among other
things that the P terms should be smaller than the hydrogen terms
D terms—penetrates partly into the region of the orbits of the
inner electrons during the course of its revolution. These investi-
gations contain without doubt important hints, but in reality the
conditions must be very different for the different alkali spectra.
Instead of a 2t orbit as in lithium we must thus assume for
the spectrum of sodium not only that the first spectral term in
the S series corresponds to a ^ orbit, but also, as a more detailed
consideration shows, that the first term in the P series corresponds
not to a 2a orbit as indicated in fig. 2, but to a 32 orbit If the
numbers in this figure were correct, it would require among other
things that the P terms should be smaller than the hydrogen terms
Fig. 3.
corresponding to the same principal quantum number. This would
mean that the average effect of the inner electrons could be described
as a repulsion greater than would occur if their total electrical charge
were united in the nucleus. This, however, can not be expected from
our view of atomic structure. The fact that the lastcaptured electron,
at any rate for low values of &, revolves partly inside the orbits of the
previously bound electrons will on the contrary involve that the
presence of these electrons will give rise to a virtual repulsion
which is considerably smaller than that which would be due to
their combined charges. Instead of the curves drawn between
points in fig. 2 which represent stationary states corresponding
to the same value of the principal quantum number running from
right to left, we obtain curves which run from left to right, as
is indicated in fig. 3. The stationary states are labelled with
mean that the average effect of the inner electrons could be described
as a repulsion greater than would occur if their total electrical charge
were united in the nucleus. This, however, can not be expected from
our view of atomic structure. The fact that the lastcaptured electron,
at any rate for low values of &, revolves partly inside the orbits of the
previously bound electrons will on the contrary involve that the
presence of these electrons will give rise to a virtual repulsion
which is considerably smaller than that which would be due to
their combined charges. Instead of the curves drawn between
points in fig. 2 which represent stationary states corresponding
to the same value of the principal quantum number running from
right to left, we obtain curves which run from left to right, as
is indicated in fig. 3. The stationary states are labelled with
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