Transition metals, also known as transition elements are usually referred to as any element in the d-block of the periodic table, expect for zinc, cadmium, and mercury. The d-block of the periodic table includes groups three through twelve. The IUPAC defines transition metals as elements whose atom has an incomplete d sub-shell, or can give rise to cations with an incomplete d sub-shell. This definition excludes zinc, cadmium, and mercury because they have completed d sub shells. Transition metals are the 40 chemical elements 21 to 30, 39 to 48, 71 to 80, and 103 to 112. The name, transition, comes from their position in the periodic table of elements.
Transition metals usually have high density, melting and boiling points, and high tensile strength. This is due to their d orbital electrons’ ability to delocalize within the lattice. In the substances, the more electrons shared between nuclei, the stronger the metal.
Transitions metals have several common characteristic properties, including the fact that they often form colored compounds, they can have a variety of different oxidation states, at least one of their compounds has an incomplete d-electron sub-shell, they are usually good catalysts, their ions are silver-blue at room temperature excluding copper, iron, and gold; they are solids at room temperature except mercury, and they form complex ions excluding aqua ions, and they are often paramagnetic.
Transitions metals are extremely useful metals on account of their physical or chemical properties. For example, cast is used for man-hole covers because it is so hard wearing, copper used in electrical wiring because it is a good conductor of electricity and is used in domestic hot water pipes because it is relatively unreactive to water and therefore doesn’t corrode easily. Zinc is used to coat iron or steel to sacrificially protect them from corrosion. Compounds of copper, iron, chromium and cobalt are used to give bright colors to stained glass.
The transition metals include scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, rutherfordium, dubnium, seaborgium, bohrium, hassium, meitnerium, ununnilium, unununium, and ununbium.