Step 1: Group the typical features under headings. Electronic: partly filled \((n-1)d\) orbitals. Chemical: variable oxidation states and strong tendency to form complexes. Physical: high melting/boiling points, high density, hardness, and alloy formation.
Step 2: Optical and magnetic: coloured ions from d-d transitions and paramagnetism from unpaired d-electrons; many also show catalytic activity.
Step 3: Naming reason: the term transition marks their bridging position, where the outer electron pattern shifts from the s-block (filling s) to the p-block (filling p) while the d-subshell is being filled in between.
Step 4: Because their atoms or common ions keep incompletely filled d-orbitals during this changeover, they are named transition metals.