To the right is an early version of the Periodic Table, developed by John Dalton in 1805. It is interesting to note that several substances which were known by chemists of the time are not represented: although they were in use, no one had yet realized that they were unique elements.
In terms of the year of their discovery, we begin with the most recent element first...
Atomic Symbol: In
Atomic Number: 49
Discovered in 1863 by Ferdinand Reich, who was investigating a metal ore which he believed contained the recently discovered element of thallium. His spectroscope revealed a series of lines which were not associated with thallium, however; and since he was color blind, he called on a colleague to examine the spectrum. What was immediately evident was a brilliant, indigo colored line from which they derived the name "indium".
Although people were interested in the element, little use has been found for it except in a few low melting-point alloys, such as those used in sprinkler systems. Indium metal will "glue' itself to glass when evaporated, producing a mirror as good in quality as that of silver but more resistant to corrosion.
Atomic Symbol: Sn
Atomic Number: 50
The chemical symbol comes from the latin stannum. When copper is alloyed with a small amount of tin, it produces bronze; which not only melts at a lower temperature, making it easier to work with, it also makes the metal harder, which is ideal for producing weapons and tools. This discovery is commemorated in the term "Bronze Age", which was a recognized stage in the development of civilizations. How bronze was discovered is unknown, but the people of Egypt, Mesopotamia, and India were using bronze by 3000 BC.
Tin can decay to dust, an effect known as "tin plague" which has been responsible for several famous disasters. The Scott expedition to the South Pole in 1912 left tin cans of fuel at vaious points on their trek. When they returned on the way back in need of fuel, the cans were found to be empty: it had drained away through tiny holes as the metal corroded. The explorers all perished as a result. Canned food which they'd left behind was found to be still edible fifty years later.
Atomic Symbol: Sb
Atomic Number: 51
Roman physicians prescribed antimony sulfides for skin conditions, but it was in the sixteenth century that antimony medications really came into vogue and were used to treat all kinds of ailments. Mozart may well have been prematurely killed by it. When he became ill his doctors prescribed antimony tartrate, and he was fond of dosing himself with it. When he died, his symptoms were identical to those of acute antimony poisoning.
In the Middle Ages, antimony metal pills were sold as reusable laxatives. People suffering from constipation would swallow a small antimony ball about the size of a pea, and its toxic action would aggravate the intestines, causing them to become more active to expel the irritant pill. It was then recovered from the excrement and stored for future use!
There's an outstanding book covering all of the elements in the Periodic Table, filled with fascinating information about each, called Nature's Building Blocks, by John Emsley.
For my previous posts on the elements, click here.