State two physical properties of Group I metals that are unusual compared to most metals.

Lithium, sodium, and potassium can all be cut with a knife. What does this tell you about their hardness compared to other metals?

Lithium has a density of 0.53 g/cm³. What physical observation would you make if a piece of lithium was placed in water?

State the appearance of a freshly cut Group I metal surface.

Group I metals are stored under oil. Suggest why they cannot simply be left in air.

Describe the trend in melting point as you go down Group I (Li → Cs).

Describe the trend in density as you go down Group I.

The melting points of lithium, sodium, and potassium are 181°C, 98°C, and 63°C respectively. Using this data, predict the melting point of rubidium (Rb).

Explain why the melting points of Group I metals are lower than those of transition metals such as iron.

Would caesium (Cs) float on water? Use the trend in density to justify your answer.

What is observed when a fresh piece of sodium is cut and then exposed to air for 30 seconds?

Potassium is cut with a knife. State two observations you would make about the physical properties revealed during this process.

A student observes that lithium floats on water and moves across the surface. What physical property of lithium causes it to float?

Group I metals are described as 'soft metals'. Describe a simple physical test that would demonstrate this property.

A student places a small piece of potassium on a watch glass and leaves it in a fume cupboard open to air. Describe two observations the student would make over 5 minutes. Explain the chemical reason for one of your observations.