Platinum

Summary: Platinum (Pt) is a dense, unreactive transition metal with atomic number 78. In IGCSE Chemistry, it is most commonly encountered as a catalyst — used in fuel cells, catalytic converters, and as inert electrodes. Tags: igcse chemistry transition-metals catalyst keyword Created: 2026-07-14 Last Updated: 2026-07-14

Platinum (symbol Pt, atomic number 78) is a dense, silvery-grey transition metal classified as a noble metal due to its exceptional resistance to corrosion and chemical attack, even by concentrated acids. Its most significant IGCSE application is as a heterogeneous catalyst: finely divided platinum provides a high surface area onto which reactant gas molecules adsorb, weakening their bonds and lowering the activation energy for reactions such as the oxidation of hydrogen in fuel cells and the conversion of toxic exhaust gases (CO, NOₓ, unburnt hydrocarbons) into harmless products in automotive catalytic converters. Platinum is also used as an inert electrode material in electrolysis experiments because it conducts electricity without participating in the reaction — an important property it shares with graphite, though graphite is cheaper and more commonly used in school laboratories. Beyond the IGCCE syllabus, platinum’s use in jewellery stems from its lustrous appearance and resistance to tarnishing, while in industry it catalyses the Contact Process for sulfuric acid production (though vanadium(V) oxide is more common there). In exam questions, students should be able to explain that a platinum catalyst works by providing an alternative reaction pathway with a lower activation energy, and they should recognise that the metal itself remains chemically unchanged at the end of the reaction.

Key term — IGCSE Chemistry (0620/0971) glossary.