Symbol (chemistry) the material was known in ancient times, while for others, the name is a more recent invention. For example, "He" is the symbol for helium (New Latin name, not known in ancient Roman times), "Pb" for lead ("plumbum" in Latin), and "Hg" for mercury ("hydrargyrum" in Greek). Some symbols come from other sources, like "W" for tungsten ("Wolfram" in German, not known in Roman times). Temporary symbols assigned to newly or not-yet synthesized elements use 3-letter symbols based on their atomic numbers. For example, "Uno" was the temporary symbol for hassium (element 108) which had the temporary name of "unniloctium".
Melting-point depression and thermal properties. This article focuses on nanoparticles because researchers have compiled a large amount of size-dependent melting data for near spherical nanoparticles. Nanoparticles are easiest to study due their ease of fabrication and simplified conditions for theoretical modeling. The melting temperature of a nanoparticle decreases sharply as the particle reaches critical diameter, usually < 50 nm for common engineering metals. Figure 1 shows the shape of a typical melting curve for a metal nanoparticle as a function of its diameter. Melting point depression is a very important issue for applications involving nanoparticles, as it decreases the functional range of