From the iron and aluminum in our cars to the zinc we take in our multivitamins, metals have a significant role in our lives. Some of the most common metals we use are called “transition metals.”
The American Heritage Dictionary of the English Language defines transition elements, also known as transition metals, as “any of the metallic elements within Groups 3 to 12 in the Periodic Table that have an incomplete inner electron shell and that serve as transitional links between the most and the least electropositive in a series of elements. They are characterized by multiple valences, colored compounds and the ability to form stable complex ions.”
Transition metals are malleable, ductile and conduct heat and electricity well. A “malleable” material is one can be worked with, such as hammered into a flat sheet. A “ductile” material can be turned into wire. Transition metals are good conductors of electricity and heat, as well. For example, copper has been used for electric wiring for decades, and is also used in making cooking utensils. Three transition metals in particular (iron, cobalt and nickel) are also capable of producing a magnetic field.
Transition metals are capable of combining with other elements to make chemical compounds. However, unlike other elements, the valence electrons, which are the electrons that join to other elements to form compounds, are found in more than one electron shell. By way of explanation, an electron is a negatively charged subatomic particle, and each atom of an element has one or more electron shells, or orbit paths. For most elements, only the outermost shell is considered the valence, where electrons can most freely join from one element to another. In a transition metal, more than one electron shell is capable of acting as a valence.
Some transition metals are good catalysts. For example, most automobiles have an emissions-control device called a catalytic converter. This device contains a screen of platinum or palladium, along with rhodium, a metal. The presence of the transition metals, along with the heat of combustion generated by an automobile engine, causes the exhaust coming from an internal combustion engine to be broken down from partially burned hydrocarbon compounds into less harmful compounds such as water vapor and carbon dioxide.
Due to their malleability, ductility and conductive properties, transition metals are used in many applications. For example, iron is used for automobile bodies and frames, food cans, building materials, and other applications where strength is needed. Copper is an excellent conductor of electricity and heat, so copper is used in applications that vary from electrical grounding posts to cooking utensils. Tungsten is used as the filament in incandescent light bulbs because it has a high melting point, and it is a good conductor of electricity. Amalgams of silver, tin, lead and copper are used to make electrical solder.