Transition Metals: Properties and Uses

The main part of the periodic table is shown in the image below. The centre part (coloured red) contains the transition metals. If you were to ask most people to describe a metal the chances are they would be describing one of the transition metals; probably silver, gold or iron. The transition metals have the properties most people associate with a metal.

When compared to the alkali metals in group 1 of the periodic table the transition metals are:

• Much harder and stronger.
• Have much higher densities and melting and boiling points.
• Are much less reactive, for example the transition metal iron reacts very slowly with water and oxygen as it rusts while transition metals such as gold and platinum do not react with water or oxygen at all.

The common properties which most people associate with metals are summarised in the image below. (click here to view more on metals)

The physical properties of metals

• Metals have a giant structure and strong metallic bonds holding this structure together.


• Metals are:
  • strong in tension: that is they can support a heavy load before they break.
  
  
  • good conductors of heat and electricity.
  
  
  • generally metals have high melting points.
  
  
  • malleable: that is they can be hammered, rolled, pressed and beaten into different shapes.
  
  
  • metals are shiny, they reflect light.
  
  
  • metals are ductile, that is they can be drawn out into wires.
  
  
  • Iron, cobalt and nickel are the only three magnetic metals.
  
  
• Metals lose their outer shell electrons when they react to form ions with a positive charge.

How are transition metals different?

I am sure you are aware that metals when they react lose electrons, so for example a group 1 alkali metal will lose 1 electron and form an ion with a 1+ charge, similarly group 2 and group 3 metals will lose 2 and 3 electrons respectively to forms ions with 2⁺ and 3⁺ charges.

The transition metals are different in that they can have variable valencies; that is they can lose different numbers of electrons depending on what they react with and on the reaction conditions e.g. Iron atoms can lose 2 or 3 electrons to form ions with a 2⁺ or 3⁺ charge. Copper can lose 1 or 2 electrons to form ions with a 1⁺ or 2⁺ charge, some metals such as manganese can form ions with charges that range from 2⁺ to 7⁺. The amazing thing is that the ions with different charges also different colours.

Transition metal compounds tend to be brightly coloured compounds whereas compounds containing metals from group 1 and group 2 are mostly colourless (white). The image below shows the wide range of colours for the transition metals manganese (present in permanganate), cobalt, chromium (present in dichromate and chromate), nickel and copper. Many of these coloured compounds containing transition metals are used to colour ceramics such as plates, pots and cups. You will also find many coloured transition metal compounds used in paints, glazes and dyes.

Common transition metals and their uses

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Many transition metals have been known for thousands of years and most have the properties we associate with metals. Transition metals such as chromium, titanium and tungsten are very hard metals used in many tools and machines. Transition metals have high melting points, with the exception of mercury which is a liquid at room temperature. Tungsten is a transition metal with the second highest melting point of any element in the periodic table, a jaw dropping 3422⁰C. Transition metals are also good electrical conductors with copper being used in wires and gold and silver being used in circuit boards in high end electronic devices.

Transition metals are also malleable; that is they can be hammered, rolled, pressed and beaten into different shapes without breaking. Most transition metals are also ductile, that is they can be drawn out and stretched into wires. Copper, gold and silver are ductile metals commonly used in wires for such things as HDMI connectors for TV and other electronic devices. Iron another transition metal is the main ingredient in steel. Steel like most transition metals has high tensile strength; this means it can support a heavy load before breaking.

Many transition metals are used as catalysts in industrial processes to speed up and increase the efficiency of the reactions taking place, iron, nickel, platinum, rhodium and palladium are transition metals which are commonly used as catalysts. Many transition metals are essential in the development of new batteries needed for electrical cars and modern electronic devices while other metals such as titanium are strong light weight metals that are used in the aerospace industry; the images opposite provide more detail on the uses of some transition metals but a quick search on-line will quickly provide you with any additional information you may need.

Transition metals as catalysts

Common examples of catalysts that you will likely meet in your studies include: the use of an iron catalyst in the Haber process for making ammonia. Platinum, palladium and rhodium are the main transition metals used as catalysts in catalytic converters in cars. These catalytic converters are very effective at reducing harmful emissions produced by unwanted reactions inside car engines. Nickel is also a transition metal that is widely used as a catalyst; for example it is used in the hydrogenation of vegetable oils; this "hardens" the vegetable oil and turns it into margarine.

Self-check

Test your understanding of the main properties and uses of transition metals by completing the paragraphs below. Simply select the correct word from the drop-down menus to complete the paragraphs. To help you complete the sentences all the words in the drop-down menus are shown in the yellow boxes.

Key Points

• Transition metals are found in the centre block of the periodic table.


• Transition metals are typical metals and have the properties most people associate with metals: strong, shiny, malleable, ductile, good thermal and electrical conductors, dense and three are magnetic (Fe, Co, Ni).


• Transition metals have variable valencies unlike groups I, II and III metals that all have fixed valencies.


• Most transition metal compounds are coloured. Group I, II and III metal compounds are almost all colourless (white).


• Transition metals are used as catalysts.


• Transition metals generally have high melting and boiling points, especially when compared to the alkali metals in group I of the periodic table. Mercury is an exception since it is a liquid at room temperature.

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