Final answer:
Transition metals are located in groups 3-12 on the periodic table and exhibit varying reactivities; inner transition metals, like lanthanoids and actinoids, are placed in two rows below the table.
Step-by-step explanation:
The transition metals are found in groups 3 through 12 of the periodic table. These elements are characterized by having partially filled d orbitals and are located in the d-block. The reactivity among these transition elements varies considerably, with some being very active, like scandium and iron, while others are quite inert, such as the platinum metals. Additionally, the inner transition metals include the lanthanoids and actinoids and are situated in the two rows below the main body of the table. These metals demonstrate a broad range of chemical behaviors and complexities in their isolation from ores.