Transition Metals

The transition metals are the metals found in the middle rectangular section of the periodic table. They make good catalysts and form coloured compounds. This topic is only on the triple science GCSE specification.

 
 

Comparing transition metals with group 1 elements

The transition metals are found in the big block in the centre of the periodic table, between groups 2 and 3. They have different properties to the metals found in group 1 (the alkali metals). Transition metals are much stronger, denser and harder than the group 1 elements. Their melting points are also much higher. For example, titanium melts at 1,668 oC, compared to potassium which melts at 63.5 oC. However, the transition metals are less reactive than the group 1 alkali metals. While a group 1 metal such as potassium reacts vigorously with oxygen, water and the halogens, transition metals react slowly or not at all. When group 1 metals react, the compounds formed are white in appearance. The compounds formed from transition metals are usually coloured.

Mounds of lithium after extracting from the ground. Lithium, like other group 1 metals, are white in appearance. Credit: Flickr/Dan Lundberg

Mounds of lithium after extracting from the ground. Lithium, like other group 1 metals, are white in appearance. Credit: Flickr/Dan Lundberg

Crystals of copper sulfate. Transition metals usually form coloured compounds. Credit: CTAGroup

Crystals of copper sulfate. Transition metals usually form coloured compounds. Credit: CTAGroup

Properties

The ions formed by transition metals can have a variety of different charges. For example:

  • Iron can form ions with a +2 or +3 charge (Fe2+ and Fe3+)

  • Chromium can form ions with a +2, +3 or +6 charge (Cr2+, Cr3+ or Cr6+)

  • Manganese can form ions with a +2, +4 or +7 charge (Mn2+, Mn4+, Mn7+)

  • Cobalt can form ions with a +2 or +3 charge (Co2+ and Co3+)

  • Copper can form ions with a +1 or +2 charge (Cu+ and Cu2+)

Transition elements react with other elements to from coloured compounds. Some examples are listed below – remember that the number given in roman numerals indicates the charge of the ion in the compound.

Precipitates of iron (II) hydroxide and iron (III) hydroxide

Precipitates of iron (II) hydroxide and iron (III) hydroxide

  • Iron (II) hydroxide is a green solid

  • Iron (III) hydroxide is a brown solid

  • Iron (II) oxide (aka rust) is an orange-brown solid

  • Copper (II) sulfate is a blue solid

Transition elements also act as catalysts, for example:

  • Iron is a catalyst used in the Haber process, in which nitrogen is reacted with hydrogen to form ammonia

  • Nickel is a catalyst in hydrogenation reactions, in which unsaturated molecules (alkenes) are converted into saturated molecules (alkanes) by reacting with hydrogen

copper sulfate room.jpg

Did you know…

In 2008 an artist called Rogen Hiorns filled an abandoned council flat in Peckham, London with 75,000 litres of copper sulfate solution. He left the solution for a few weeks before draining the flat, leaving behind crystals of bright blue copper sulfate adorning the walls and ceilings. Image credit: Nick Cobbing

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