The main part of the periodic table is shown 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.

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

• Metals have a giant structure and strong metallic bonds holding this structure together
• Metals are:
  • strong in tension: support a heavy load before they break.
  • good conductors of heat and electricity.
  • generally metals have high melting points.
  • malleable: can be hammered and beaten into different shapes.
  • metals are shiny, they reflect light.
  • metals are ductile, 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 ions with a + 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 electrons and form an ion with a 1+ charge, similarly group 2 and group 3 metals will lose 2 and 3 electrons respectivley 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 are also a different colour.

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 and dyes.

Common transition metals and their uses

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. 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 used the circuit boards in high end electronic devices.

Transition metals are also malleable, that is they can be hammered and beaten into different shapes. 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. The steel cables in this bridge support are obviously very very strong!

Transition metals as catalysts

The fact that transition metals do not have fixed valencies but have ions with many different positive charges makes them useful as catalysts e.g. iron is the catalyst used in the Haber process for making ammonia. Platinum, palladium and rhodium are the main metals used as catalyst in catalytic converters in cars. These catalytic converters are very effective at removing harmful emissions produced by unwanted reactions inside car engines. Nickel is transition metal used in the hydrogenation of vegetable oils, this "hardens" the oil and turns it into margarine.

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 3 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.

Practice questions

Check your understanding - Questions on Transition metals.