Transition elements
The transition elements form the central block of the Periodic Table (for example iron, copper and zinc). They are typical metals but have special features that set them apart from Group I metals.
Key idea
Transition elements are hard and strong, with high densities and high melting points. They form coloured compounds, show variable oxidation states, and often act as catalysts.
Useful properties
- Coloured compounds – e.g. copper(II) salts are blue, iron(II) compounds pale green, iron(III) compounds red-brown.
- Variable oxidation states – iron forms Fe2+ and Fe3+.
- Catalysts – iron in the Haber process, vanadium(V) oxide in the Contact process.
Noble gases (Group VIII / 0)
The noble gases (helium, neon, argon) have a full outer electron shell, so they are very unreactive (inert) and exist as single atoms (monatomic). Helium's low density is used in balloons; argon provides an inert atmosphere in lamps and in welding.
Remember
- Transition metals: coloured compounds, variable oxidation states, catalysts.
- Noble gases: full outer shell → inert and monatomic.