Transition Elements

Transition Elements

Transition elements, or metals, are a category of materials in the periodic table that are set apart from the "major group" or "A series" elements by their ability to use either the penultimate and outermost electron shells to bond with other substances. In industrial chemistry , transition metals are especially valuable when in their metallic state. Most of the economically important metals (i.e., silver, gold, platinum, nickel, and copper) belong to the transition elements family, as do most of the elements used when high-performance metals are necessary.

One characteristic all the transition elements have in common, besides being metals, is their incomplete d electron orbitals, which fill as atomic number increases. This is partly why transition elements are so useful--the empty orbitals help them accommodate a wide variety of bonding interactions, which makes them good catalysts.

Chemists sometimes differ on which elements should be put in the transition category. Part of this confusion stems from whether the definition of "transition" can be taken to mean that an element's orbital was just completely filled or not. In general, based on this definition, the first three series (as viewed on the periodic table) include elements 21 though 30 (scandium through zinc), 39 through 48 (yttrium though cadmium), and 57 and 72-80 (lanthanum through mercury). The fourth group of transition metals comprises elements 89, 104-109, and the undiscovered elements 110 and 111. There is another group of transition metals called the "inner transition" elements, which comprise the lanthanides (58-71, cerium to lutetium), and the actinides (90-103, thorium to lawrencium). The inner transition elements differ only in the number of f-electrons in their penultimate shell. All have very similar characteristics, their outer-shell orbitals having the same number of electrons.

Like typical metals, the transition metals are mostly hard and strong. They conduct electricity and heat, have high densities, and boil and melt at high temperatures. However, unlike regular metals, the transition elements can easily form extremely stable coordination complexes. Some of these are widely used to recover metal from low-grade ores and to facilitate high-quality electroplating. Transition metals also produce complex ions, which are often intensely colored, and frequently have unpaired electrons in their d subshells. The latter property makes such transition elements paramagnetic, meaning their magnetic moments are roughly parallel. These metals will be attracted to a magnetic field.

One of the most important reasons that many industries require transition metals is because the elements produce metal oxide compounds. Oxidationusually causes corrosion, but the transition metal oxides have many useful characteristics. For instance, they have key roles in electronics, and their use as pigments makes paint much more weather resistant. The transition metal oxides' chemical stability makes them able to stand up to intense sun and years of exposure to the open air, so they are popular in the high-end automotive and house paint industries. The oxides also impart their colors to such pigments. Those with completely empty or full 3d subshells, for example, are white (zinc oxide and titanium oxide), but they come in a wide range of vibrant colors as well.