Reactivity series

Aluminium is used in aircraft due to its low density. This reduces the overall weight of the aircraft, improving fuel efficiency and performance.

Aluminium is suitable for overhead cables because it possesses both low density and good electrical conductivity. Low density minimizes the load on support structures, while good conductivity ensures efficient power transmission.

Aluminium is used in food containers due to its resistance to corrosion. This prevents the aluminium from reacting with the food, preserving its quality and safety.

Copper is used in electrical wiring because of its good electrical conductivity and ductility. High conductivity allows for efficient electron flow, and its ductility allows it to be drawn into wires easily.

No, Group 1 metals do not exhibit catalytic behavior. Transition metals are more commonly used as catalysts.

Possible observations include: the potassium moves/floats on the water's surface; it dissolves/disappears as it reacts; bubbles/effervescence/fizzing occurs; a lilac flame is produced; the potassium may explode; the potassium melts/forms a spherical shape.

2K(s) + 2H₂O(l) → 2KOH(aq) + H₂(g). This equation shows that potassium reacts with water to produce potassium hydroxide and hydrogen gas.

Transition elements generally have higher melting points compared to Group 1 elements. This is due to stronger metallic bonding.

Transition elements generally have higher densities than Group 1 elements. This relates to the size and arrangement of their atoms.

The solution changes from colourless to orange/brown. This is because bromine is displaced.

In the reaction between chlorine and potassium bromide, bromine is displaced. Chlorine gains electrons and is reduced.