The 31st day of the month brings us to number 31 of our elemental look at the Washington Capitals. Fearless…the keyboard is yours.
Gallium is an element in search of a role. At the moment it is something of a johnny-one-note of the periodic table, with almost all of its uses coming in the field of electronics. Microwave circuits, semiconductors, light emitting diodes…those are the sorts of applications in which you find gallium. You will not find it in many, if any, biological applications. To the extent it is found there, it is largely limited to those in which it can mimic the behavior of iron. It can be used, however, as a reflective surface. When coated on glass it makes for a brilliant mirror.
Gallium is a physically unimposing element. It is soft, by metals’ standards, and it is brittle at room temperature. When it diffuses into other metals, it makes them more brittle as well. It will melt in your hand. In fact, chemists, being the pranksters that they are, love to pull off this prank at tea parties with spoons made of gallium that look like fine silver…
We do not recommend drinking the tea (really...).
Although Gallium has a low melting point (evidenced by its ability to melt in your hand), it has an extremely high boiling point. In fact, it has the greatest ratio of boiling point to melting point (measured on an absolute temperature scale) of any element. Put another way, it is a liquid over a very wide temperature range. It does not react with air or water, owing to what is referred to as a passive layer – an oxide layer that forms on its exposed surface that makes it unreactive. To the casual eye, it behaves a bit like water. It “wets” surfaces such as glass or even your hand (it will cling to them in its liquid state), and it is another of those rare substances that expands when it freezes. It does not exist in free form in nature, but rather in other substances, such as gallite, bauxite, and coal.
We are looking at a physically unimposing element that has not reached a level of mainstream applications, one that exists in nature only in the presence of other elements. It is not particularly reactive with other elements, and it is characterized as soft or brittle, but it can be brilliant in some applications.
Gallium…the “Stanislav Galiev” of the periodic table of the elements.