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Transition metal

physical science Maturity 11-13 Next article →

Transition metals are a special group of elements found in the middle of the periodic table. They live in the d-block, which includes groups 3 through 12.

First row of transition metals
First row of transition metals

These elements are very useful because they have unique physical properties. Most are shiny, or lustrous, and they carry heat and electricity very well. They are also quite hard and strong. Many of them have very high temperatures for melting and boiling. This makes them very different from many other types of elements.

These metals work in a special way because of their electrons. In the d-block, atoms have between zero and ten d electrons. These electrons live in a part of the atom called a d sub-shell. Because these electrons are often unpaired, many transition metals are paramagnetic. This means they are attracted to magnets. In fact, the only elements that are ferromagnetic near room temperature are iron, cobalt, and nickel.

Transition metal oxidation states
Transition metal oxidation states

These metals can also form many different colored compounds. This happens when they bind to other molecules called ligands.

An English chemist named Charles Rugeley Bury first used the word "transition" in 1921. He was talking about a transition series of elements. He noticed how an inner layer of electrons changes during certain steps. This change happens as electrons move from a stable group of 8 to a group of 18, or from 18 to 32. Today, we call this area the d-block.

Transition metal oxidation states 3
Transition metal oxidation states 3

Scientists still study how these electron layers work in different rows.

There are many different rows of these metals. The first row, or 3d series, starts with scandium (Z=21) and goes to zinc (Z=30). The second row is the 4d series, starting with yttrium (Z=39) and ending with cadmium (Z=48). The third row is the 5d series, which includes lutetium (Z=71) through mercury (Z=80).

Coloured-transition-metal-solutions
Coloured-transition-metal-solutions

The fourth row is the 6d series. Some elements like zinc, cadmium, and mercury are sometimes left out of the group. This is because their d shells are already full.

You can see these metals working in many things you know. They are used to make alloys, which are mixtures of different metals. They also act as catalysts. A catalyst is a substance that helps a chemical change happen. Transition metals can be used in their pure form or as oxides. Even the lanthanide and actinide elements are sometimes called inner transition metals. They belong to the f-block and have their own special way of working.

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File:First row of transition metals.jpg
First row of transition metals.jpg
File:Coloured-transition-metal-solutions.jpg
Coloured-transition-metal-solutions.jpg
File:Transition metal oxidation states.svg
Transition metal oxidation states.svg
File:Transition metal oxidation states 3.png
Transition metal oxidation states 3.png
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