Why are transition metals relatively low in the reactivity series?

Transition metals are relatively low in the reactivity series due to their stable electron configurations and high ionisation energies.

Transition metals, which include elements like iron, copper, and nickel, are found in the middle of the periodic table. They are characterised by their ability to form stable, partially filled d-orbitals. This stability is a result of the unique electron configuration of transition metals, where the outermost s and d orbitals are involved in chemical bonding. This configuration allows for a more even distribution of electron density, which in turn reduces the reactivity of these metals.

Another factor contributing to the low reactivity of transition metals is their high ionisation energies. Ionisation energy is the energy required to remove an electron from an atom. Transition metals have high ionisation energies because of the strong attraction between the positively charged nucleus and the negatively charged electrons. This strong attraction makes it difficult to remove an electron, thus reducing the reactivity of the metal.

Furthermore, transition metals often form positive ions with different charges. This is because they can lose electrons from both the s and d orbitals. The ability to form ions with different charges adds to the stability of transition metals, further reducing their reactivity.

In contrast, elements at the top of the reactivity series, such as alkali metals and alkaline earth metals, have low ionisation energies and unstable electron configurations. These elements readily lose electrons to form positive ions, making them highly reactive.

In summary, the low reactivity of transition metals can be attributed to their stable electron configurations and high ionisation energies. These properties make transition metals less likely to participate in chemical reactions compared to other elements in the periodic table.