What Are Transition Metals?

Mary McMahon
Mary McMahon

Transition metals are chemical elements that share the unusual trait of splitting the valence electrons that can form chemical bonds with other elements between the two outer shells of their structure. Normally, only the outermost shell can contribute valence electrons. This unique behavior leads to some distinctive properties that make the transition metals stand out from other elements. They have a number of oxidation states, for example, and tend to form very stable bonds with a variety of elements.

The transitional metal elements can be seen around the middle of the periodic table.
The transitional metal elements can be seen around the middle of the periodic table.

These elements can be found around the middle of the periodic table and occupy most of the region known as the d-block. Some simplistic definitions describe transition metals simply as d-block elements, but this is not quite correct. Not all d-block elements fit within this categorization, although many do. A few elements, like zinc, tend to be topics of dispute and may be variably classified in and out of the transition metals. Some of the transition metals are also toxic and can pose a threat to human or environmental health and safety.

Iron is an example of a transition metal on the periodic table.
Iron is an example of a transition metal on the periodic table.

With the exception of mercury, which is a liquid, transition metals tend to be very hard. They are also brittle and have an extremely high melting point. Their energy states make them excellent conductors, and many are used in the fabrication of electronics components because of their good conduction. These metals can be found in many regions of the world and many are mined commercially for use in manufacturing.

Some examples of transition metals include iron, copper, cobalt, nickel, gold, platinum, and manganese. Within the transition group, there is tremendous diversity. Some of these elements, for instance, are necessary dietary nutrients that people need to consume in trace amounts for their health. Others appear naturally in several different forms, depending on the structure of their outer shells. The variance within this broad grouping is one of the reasons it is often hard to categorize transition metals.

Many periodic tables color code the elements by group for convenience. Astute observers may notice that the elements coded as transition metals can vary, depending on conventions at a given time or in a particular region. Students should make sure to use the definition used by their instructors, and should request clarification if they are not sure about whether an element is considered a member of this group. The instructor's opinion on the matter can be a deciding factor on something like a chemistry test, and it is important to use the answer the instructor would expect.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


@framemaker- There is actually some debate over whether mercury is a transition metal. Mercury, zinc, and one other element (cannot quite remember), lie on the cusp of the transition metals, and have some unique features. While mercury has many of the characteristics of a transition metal, it also shares properties with other metals and elements. The debate over transition elements like zinc and mercury will rage on, but I just wanted to clarify an area where there is disagreement within the scientific community.


@PelesTears- The rare earth elements are the lanthanides, yttrium, and scandium. The elements are actually abundant, but they receive their rare earth designation because of the scarcity of the elements in high concentrations. The lanthanides along with the actinides make up the inner transition metals. They share many properties with the other transition metals.

These metals can be used for a number of things. Lanthanum is crucial to the hydrogen industry, and is important in creating battery electrodes and for use in hydrogen storage. The various super magnets used in things like wind turbines and electric motors use neodymium and praseodymium. Various other inner transition metals are used for such things as lasers, lighting, and nuclear applications.

All of these uses are high tech uses, and many are critical to revamping the nation's energy industry. As far as I know, China has some of the best and only economically feasible reserves of these elements on the planets.


What are the physical and chemical properties of transition metals? What differentiates these metals form the other metals in the periodic table of elements?


@valleyfiah- Mercury is one of the most unique elements in the periodic table. The metal is only one of two elements that are liquid at standard temperature and pressure (stp). Mercury also has a very short temperature range between the freezing and boiling points. Mercury is the only transition metal with these properties.

The actual temperature that mercury turns to a solid is around 40 degrees below zero Fahrenheit. The material has unique properties that have led to its use in a number of applications, ranging from rocket propellants, medical treatments, and coolant for nuclear power reactors.

One of the applications I find most interesting is its use as a turbine fluid and rocket propellant. The low ionization energy, high density and molecular mass, and the fact it is stable as a liquid at room temperature made the element a good candidate for ion engines. If it were not for the toxicity and the fact that it is extremely rare in the earth's crust were mercury's biggest downside as a propellant.


Are all transition metals rare earth metals? How do rare earth metals accumulate? What country has the largest reserves of rare earth metals? I hear a lot in the news about how China is affecting the United States because it is protecting its rare earth metals.

A discussion came up about China and their passive aggressive competition with the United States and rare earth metals. The discussion centered on the importance of rare earth metals to the U.S economy, and the effect that China's policies to protect these resources is having on the United States. It was an interesting topic, and I just wanted to learn more about these rare earth metals. What are they used for and how do they form? I understand the economic aspect of protecting these resources, but I do not know exactly what these resources or their uses are.


What temperature is mercury a solid? Someone told me that mercury actually has a solid state, but it is at a lower temperature than ambient temperature. If this is true, I would also like to know why mercury has such a low melting point compared to most metals that melt at high temperatures. I do not know much about the properties of transition metals, but I would be curious to learn a little more. I never really paid attention to this type of stuff in school, but now I am interested in knowing more about the world I live in.

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