The chemical and biochemical properties of molecules depend on the shape, charge, preferred charge, actual charge and distribution of charge over the molecule.
Metals usually conduct electric currents and heat better than non-metals. Most metals can be hammered into shape, and many can be melted and poured into moulds.
Metals are elements with a few electrons only in the outermost shell. These electrons are only loosely held, and this is why metals conduct electricity.
Many materials are melted more easily by adding them to a flux which melts at a low temperature than they do, and effectively takes the material into solution.
The melting points and boiling points of all materials can be measured. For pure substances under the same conditions, these values always remain constant.
One common test for the purity of organic chemicals (including some drugs of addiction) is to measure their melting points, which will be lowered by impurities.