Chlorine is a halogen and is located in the same group as fluorine, which is the most reactive element in the periodic table. Halogens are known for their high electronegativity, meaning they have a strong attraction for electrons, which makes them very reactive. Chlorine gas is a toxic gas that can cause severe respiratory problems and can even be fatal if inhaled in large amounts.

Aluminium, on the other hand, is a metal and is located in the same group as boron and gallium. Metals are generally less reactive than non-metals, and aluminium is no exception. Aluminium is known for its resistance to corrosion and oxidation, which makes it useful for a variety of applications such as construction, transportation, and packaging.