The alkali metals:
The alkali metals also have low densities. They are low enough for the first three (lithium, sodium and potassium) to float on water.
The table shows the melting points of five alkali metals. Use this information to describe how melting point changes in group 1.
Going down group 1, the melting point decreases.
Use the information in the table to predict the melting point of francium, Fr. Explain your answer.
The melting point of francium will be around 23°C. This is because francium is below caesium in the periodic table, so it should have a lower melting point, and the difference in melting point decreases going from one element to the next. The actual melting point is 21°C.