The
transition metals are inserted between Groups IIA and IIIA, beginning
with Row 4. They are given group numbers that continue the numbering
of the representative elements, but their numbers are followed by
B instead of A. Group IIIB follows IIA in Row 4, then comes IVB
through VIIIB, followed by IB and IIB, and a resumption of the representative
elements with IIIA. This numbering is shown on the table at the
left. The inner transition metals are so much less important that
they are not given group numbers at all. In this chapter we shall
look for the last time at the representative elements as a whole,
introduce the transition metals, and have very little to say about
the inner transition metals.
Representative elements reflect the filling of
s and p orbitals, transition metals of f orbitals.
The extra-long form of the periodic table at the top shows the filling
of the orbitals in their proper order, but is large and clumsy. The
standard long form of the table below it removes the inner transition
metals to as separate block, and the short form shown on the previous
page also separates out the transition metals