text: These elements undergo oxidative additions and reductive eliminations.
full_question: These elements undergo oxidative additions and reductive eliminations. The sum of group number,charge, and the number of covalent and dative bonds is used to count electrons for these elements, andthat number adds up to around 18. The N plus L rule was formulated after observing that some of theseelements lose an electron from their valence shell to half-fill a (*) lower-energy shell. Most heterogeneouscatalysts are composed of these elements. The orbitals of these elements split according to crystal field theory,which explains why solutions of them are often colorful. Lewis bases coordinating these elements form octahedralcomplexes and are called ligands. For 10 points, name these elements with unfilled d orbitals, which occupy thecenter of the Periodic Table.
first_sentence: These elements undergo oxidative additions and reductive eliminations.
raw_answer:  transition metals [or transition elements; prompt on metals]