Transition metals refer to the 38 elements from groups three to 12 on the periodic table. They are hard, ductile, malleable and capable of conducting heat and electricity. They often have several common oxidation states, because their valence electrons exist in more than one shell.
The five d orbitals become more filled, starting from left to right on the periodic table. The loosely bound d electrons contribute to the high malleability and electrical conductivity of the elements.
Transition elements have low ionization energies. They have a wide range of positively charged forms or oxidation states. Positive oxidation states enable these metals to create numerous different ionic and partially ionic compounds. The d orbitals separate into two energy sublevels due to the formation of complexes. This allows most of the complexes to absorb particular frequencies of light, forming characteristic colored compounds and solutions.
Three noteworthy transition elements are iron, nickel and cobalt, which are the only elements that produce a magnetic field. Generally, these metals have high melting and boiling points. Moreover, they typically form colored compounds. Another property of transition metals is that they are often paramagnetic.
The most abundant transition elements are iron and titanium. Important transition metals include silver, copper and iron. Many of these elements serve as catalysts for industrial reactions.