Transition Metals

Transition metals are a group of metals located in the centre of the periodic table, between groups 2 and 3 (or 2 and 13, depending on the table).

The periodic table with non-metals highlighted in purple, metals highlighted in green, and transition metals highlighted in blue.

As you can see, most of the known metals are transition metals.

Properties of Transition Metals

Transition metals have typical properties of metals:

  • Appearance – These metals have a shiny and reflective appearance.
  • Malleability and Ductility – They are malleable, meaning that they can be shaped without breaking, and ductile, meaning that they can be stretched into wires.
  • Good Conductors – They conduct electricity well, both in solid and liquid states.

Despite these similarities, they have notable differences compared to group 1 metals:

  • Hardness and Strength – They exhibit greater hardness and strength than group 1 metals.
  • Higher Density – They have densities that are higher than group 1 metals.
  • Lower Reactivity – They are generally less reactive than group 1 metals, with some being completely unreactive.
  • Higher Boiling Points – With the exception of mercury, they have higher boiling points.

It’s also worth noting that transition metals can form ions with different charges. The table below shows some examples of transition metals and their common ions.

MetalCommon ions
Chromium (Cr)Cr²⁺, Cr³⁺, Cr⁶⁺
Manganese (Mn)Mn²⁺, Mn³⁺, Mn⁴⁺, Mn⁶⁺, Mn⁷⁺
Iron (Fe)Fe²⁺, Fe³⁺
Cobalt (Co)Co²⁺, Co³⁺
Nickel (Ni)Ni²⁺
Copper (Cu)Cu, Cu²⁺

The table below compares the melting points and densities of the first three group 1 metals with the transition metals above.

MetalGroupMelting pointDensity
Lithium (Li)Group 1181 °C0.53 g/cm³
Sodium (Na)Group 198 °C0.97 g/cm³
Potassium (K)Group 164 °C0.89 g/cm³
Chromium (Cr)Transition metal1890 °C7.19 g/cm³
Manganese (Mn)Transition metal1240 °C7.20 g/cm³
Iron (Fe)Transition metal1538 °C7.87 g/cm³
Cobalt (Co)Transition metal1492 °C8.90 g/cm³
Nickel (Ni)Transition metal1453 °C8.90 g/cm³
Copper (Cu)Transition metal1083 °C8.92 g/cm³

As you can see in the table, the melting points and densities of the transition metals are higher compared to the group 1 metals.

Transition metals form compounds with different colours based on the charge of the metal ion.

The colours of different metal ions.

The most important ones to remember are:

  • Copper (II), Cu2+ Copper ions in a +2 charge state form compounds with a distinctive blue colour
  • Iron (II), Fe2+ Iron ions in a +2 charge state form compounds with a green colour
  • Iron (III), Fe3+ Iron ions in a +3 charge state form compounds with an orange-brown colour

Using Transition Metals as Catalysts

A catalyst is a substance that speeds up the rate of reaction without being used up in the process. Transition metals are often used as catalysts. For example:

  • Iron is the catalyst in the Haber Process to make ammonia.
  • Nickel is used as a catalyst in the hydrogenation of alkenes to produce alkanes.