Hafnium is a metal element which has a bright silver luster. Its atomic symbol is Hf and its atomic number is 72. Its melting point is 4,051.4 ± 68°F (2,233 ± 20°C), its boiling point, 8,317.4°F (4,603°C), and it has an atomic weight of 178.49. Reports of its physical properties sometimes differ, probably because of the presence of zirconium as an impurity in the sample.

The discovery of hafnium was made during the early part of the twentieth century. By 1920, all but a handful of the elements had been discovered. Based on three empty spaces in Henry Moseley's version of the periodic table, chemists knew that elements 43, 61, and 72 had yet to be discovered. They also knew a great deal about the chemical and physical properties of the missing elements. Chemical theory had advanced to a point where researchers had a reasonably good idea as to where to look and what...