Periodic Table of Elements
Dmitri Mendeleev (1834 - 1907) introduced the periodic table in 1869. The table is organised into vertical groups and horizontal periods. Elements are placed along each period in order of their atomic number, with elements 1-2, 3 -10, 11-18 etc. all in the same horizontal row of the periodic table. The first element in the table with the atomic number 1 is hydrogen. Groups of elements have similarities in characteristics e.g. group 17 - known as halogens.
- The Transition metals across the centre of the table have a strong association with pigments used by artists. Gold is valued for its colour. Other transition metals form compounds where the combined electric fields of the surrounding ions modify the energies of the electrons on the metal ion.
- The reactive metals on the left of the periodic table are used as a colouring agent in fireworks where they burn in the presence of an oxidizing agent resulting in bright colours lighting up the night sky. Reducing agents such as sulphur and charcoal are then used to control the rate of the reaction.
Alchemists in the Middle Ages sought the existence of a material vital to the transmutation of base metal into gold or silver. They identified the philosopher's stone with a quinta essentia, a fifth being over and above the four classical elements, and with the ability to facilitate the transmutation of materials: the quinta essentia, a universal substance of which all other materials are composed, therefore being the essence of life. Of the search for a substance, called the philosopher's stone, Geoffrey Chaucer wrote that:
"Then thus conclude I, since that God of heaven
Will not that these philosophers neven
How that a man shall come unto this stone,
I as for the best to let it gon.
For whoso maketh God his adversary,
As for to work any thing in contrary
Of his will, certes never shall he thrive,
Though that he multiply term of his live."
The idea of the transmutation of the elements probably arose among the Alexandrian Greeks in the early centuries of the Christian era; and from there it passed to the Arabs. Geber (c.760-c.815), who was the author of many works on alchemy proposed the theory that all matter is combined in mercury and sulphur, and it remained only to find some material that would facilitate the mixture of mercury and sulphur in the proper proportions to produce gold. From the Arabs knowledge of the arts of alchemy was transferred to western Europe. The importance of transmutation was challenged by Paracelsus (1493 - 1541), "Many have said of Alchemy, that it is for the making of gold and silver. For me such is not the aim, but to consider only what virtue and power may lie in medicines." Robert Boyle (1627-1691) investigated the transmutation of metals; in 1676, he reported to the Royal Society on his attempts to change quicksilver into gold, and believed that he was near success in this endeavor. He did make a break with the alchemists' tradition of secrecy with his conviction and insistence on publishing in great experimental detail. In their search for formulations for producing silver and gold, the alchemists had already been convinced that precisely measured proportions are essential, an empirical approach to study.
Can you turn this base metal into gold? It's alchemy!
There are four classical Greek elements: air / wind, earth, fire and water:
- air / wind
Plato provided a description of the four classical elements, in which the elements are composed of atoms each of which has a geometric shape. Aristotle provided an extended description of the four elements in which a quality is attached to an element such that there are four qualities, each of which is shared by a pair of elements, with the combination providing a fifth element the "quintessence." The four classical elements were accepted as theory for over 2000 years, and Aristotle's theories were accepted throughout the Middle Ages, when they were incorporated into the art of alchemy. The alchemists associated each of the classical elements with a symbol:
Robert Boyle (1627-1691) explained how:
"...the Antients, though they did not all Agree about what kind of Bodies were Mixt, yet they did almost unanimously hold, that in a compounded Bodie, though the Miscibilia, whether Elements, Principles, or whatever they pleas'd to call them, were associated in such small Parts, and with so much Exactness, that there was no sensible Part of the Mass but seem'd to be of the same Nature with the rest, and with the whole; Yet as to the Atomes, or other Insensible Parcels of Matter, whereof each of the Miscibilia consisted, they retain'd each of them its own Nature, being but by Apposition or Juxta-Position united with the rest into one Bodie. So that although by virtue of this composition the mixt Body did perhaps obtain Divers new Qualities, yet still the Ingredients that Compounded it, retaining their own Nature, were by the Destruction of the Compositum separable from each other, the minute Parts disingag'd from those of a differing Nature, and associated with those of their own sort returning to be again, Fire, Earth, or Water, as they were before they chanc'd to be Ingredients of that Compositum".