What is the pattern between melting point and atomic radius?
A general relation doesn't exist.
What is the relationship between the atomic number of an element and its atomic radius from the graph of your lab report?
A very general rule of thumb is that as atomic radius increases, melting point goes down. It's an inverse relationship. And atomis radius (generally) increases moving down the columns of the periodic table. As atomic radius increases, the atoms lose their ability to "stick together" and resist a change of state. Smaller atoms require more heat to melt or boil (vaporize) them because their smaller radaii allows the "reach" of the electrostatic charge of the…