Fourth and fifth rows have reactive elements {transition metal}, with many ionic forms, whose outermost electrons are in d orbitals, not in higher p orbitals. Metals in columns 4 to 16 have 10 d electrons.
Sixth row has elements {inner transition metal} with one or two electrons in d orbital and outermost electrons in f orbitals. Lanthanides and actinides {rare earth}, as well as scandium and yttrium, are solids.
First inner-transition-metal row {lanthanide series}, from element 58 to 71, is solids.
Second inner-transition-metal row {actinide series}, from element 90/91 to 103, is solids.
5-Physics-Matter-Atom-Periodic Table
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Date Modified: 2022.0225